You’re staring at the giant plastic numbers on the corner sign, and there it is. That tiny, annoying fraction. 9/10. It’s been there your entire life. It’s on every single gas station sign from Maine to California, yet we never actually use tenths of a cent for anything else. You can't hand a cashier nine-tenths of a penny. It’s physically impossible. Honestly, it feels like a glitch in the matrix that just became a permanent feature of the American landscape.
Most people assume it’s just a marketing trick to make gas look cheaper. You know, like how a shirt is $19.99 instead of $20.00. That’s part of it, sure. But the real story is a lot more bureaucratic and dates back to a time when a gallon of gas cost about 15 cents.
The Great Depression and the Birth of the Fraction
Why do gas prices have 9/10 of a cent in the first place? It isn't just a random choice made by a greedy oil executive in a smoke-filled room. It actually started with the federal government. Back in 1932, the United States was in the thick of the Great Depression. Money was tight, the budget was a mess, and Congress was looking for ways to generate revenue.
They passed the Revenue Act of 1932. This introduced a federal gas tax of 1 cent per gallon.
Now, here is where it gets weird. They didn't just stop at a full cent. Because gas was so cheap back then—literally pennies—the government and gas station owners needed to be able to adjust prices in tiny increments to stay competitive while still covering the tax. Eventually, the tax was adjusted by fractions of a cent.
Gas stations didn't want to just absorb these fractional tax increases. They also didn't want to round up to the next full cent because, in a world where gas is 10 cents a gallon, a 1-cent jump is a massive 10% price hike. Imagine gas jumping from $3.50 to $3.85 overnight just because of a rounding error. People would lose their minds. So, they just tacked the fraction onto the price at the pump. By the time the 1950s rolled around and the Interstate Highway System was being built, the 9/10 fraction had basically become the industry standard.
It Is Mostly Psychological Warfare Now
Let’s be real. The tax reason is the historical "why," but the reason it's still here in 2026 is pure psychology. It’s called "left-digit pricing."
Our brains are lazy. When we see $3.49 and 9/10, we don't think "that’s basically three dollars and fifty cents." We focus on the 3 and the 4. We perceive it as significantly cheaper than $3.50. It’s a trick of the light, a cognitive bias that retailers have exploited for nearly a century. If a station across the street rounds down to $3.49 and you stay at $3.50, you’re going to lose the price war.
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It’s a race to the bottom, or at least a race to the appearance of the bottom.
Robert Schindler, a professor of marketing at Rutgers-Camden who has spent years studying how consumers respond to prices, has noted that these "9-ending" prices are incredibly effective. Even though we know we’re being manipulated, the subconscious lizard brain still prefers the lower leading digit. It feels like a bargain. Even if that bargain is literally one-tenth of one cent.
The Math of the "Micro-Penny"
You might think a tenth of a cent is meaningless. To you, it is. If you fill up a 15-gallon tank, that 9/10 of a cent adds up to... 13.5 cents. You probably wouldn't bend over to pick that up off a dirty sidewalk.
But look at it from the perspective of a gas station owner or a massive corporation like ExxonMobil or Shell.
Americans consume roughly 370 million gallons of gasoline per day. If you collect an extra 0.9 cents on every single one of those gallons, you’re looking at over $3.3 million in additional revenue every single day across the industry. Over a year, that’s more than a billion dollars. It’s "found money" built into a rounding error.
Why Don't We Just Kill the Fraction?
There have been attempts to stop this madness. Some independent gas station owners have tried to simplify things by rounding to the nearest penny.
It usually fails.
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Back in the mid-2000s, a station owner in Iowa tried to market his gas without the 9/10. He rounded his prices to the whole cent. What happened? Customers stayed away. They thought he was more expensive than the guy down the street who was still using the fraction. It turns out, we are our own worst enemies when it comes to transparent pricing. We claim to hate the 9/10, but we vote for it with our wallets every time we pull into the station that looks a fraction of a cent cheaper.
There’s also the issue of the pumps themselves. Gas pumps are highly regulated pieces of hardware. The software and the physical displays are designed to calculate out to the third decimal point. Changing the entire infrastructure of American fuel delivery just to get rid of a fraction that most people have learned to ignore isn't exactly a high priority for the weights and measures departments.
The Stealth Price Hike
Another reason the 9/10 stays? It gives stations a way to move prices without people noticing as much. If you see gas go from $3.45 to $3.49, you might shrug. But that 4-cent jump is actually 4.0 cents, and the 9/10 is always sitting there like a silent sentinel.
Interestingly, in some countries, they’ve actually moved away from this. In parts of Europe and Canada, while fractional pricing still exists in some retail spaces, many places have moved toward more rounded, transparent figures as they phased out smaller denominations of physical currency. But in the U.S., where the penny is still clinging to life (despite costing more than a cent to mint), the 9/10 of a cent isn't going anywhere.
The Evolution of the Gas Sign
Think about how much the signage has changed. We went from manual flip-cards to those bright LED displays that can be changed with a smartphone app from the manager's office.
Despite all that tech, the 9/10 is still usually a static, smaller number. Sometimes it’s even physically printed on the sign while the other numbers are digital. It’s a permanent part of the visual branding of a gas station. If you saw a sign that just said "$3.50," you’d probably think the station was closed or the sign was broken. It looks "wrong" to our eyes now.
Is It Ever Going To Change?
Probably not. At least, not as long as we’re primarily using liquid fuel.
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As we shift toward Electric Vehicles (EVs), the pricing model is changing. If you look at Tesla Superchargers or Electrify America stations, they usually charge by the kilowatt-hour (kWh). Most of these are priced in whole cents, like $0.32 or $0.41 per kWh.
There is no "9/10 of a cent" at most EV chargers.
This suggests that the fraction is a relic of the petroleum age. It’s a vestigial organ of the fossil fuel industry. Once we stop buying gas by the gallon, the 9/10 will finally die. But for the millions of internal combustion engines still on the road, that tiny fraction is a permanent passenger.
What You Should Actually Care About
If you’re worried about that extra 13 cents on your fill-up, you’re looking at the wrong part of the receipt. The real price fluctuations come from things that actually matter:
- Crude Oil Prices: This accounts for roughly 50% of what you pay at the pump. When OPEC+ decides to cut production, that has a way bigger impact than a tenth of a cent.
- Refining Costs: Different regions have different "blends" of gas. Summer blends are more expensive to produce than winter blends to prevent evaporation, which is why prices often spike in May.
- State Taxes: This is the big one. If you drive across a state line, you might see a 30-cent difference immediately. That has nothing to do with the 9/10 and everything to do with how that state funds its roads.
- Distribution and Marketing: The cost of getting the gas from the refinery to your local station in a truck.
Actionable Steps for the Savvy Driver
Since you can't get rid of the 9/10, you might as well beat the system in other ways. Don't let the psychological trickery of fractional cents dictate where you buy fuel.
- Ignore the Fraction: When looking at gas signs, always round up in your head. If it says $3.59 and 9/10, tell yourself it’s $3.60. This removes the "left-digit" bias and lets you compare prices more accurately.
- Use Apps, Not Eyes: Don't just pull into the first station you see. Apps like GasBuddy or even Google Maps show real-time prices. Often, a station two blocks away is 15 to 20 cents cheaper, which vastly outweighs any fractional cent savings.
- Check for Rewards: Many grocery chains and credit cards offer cents-off-per-gallon rewards. These usually come in increments of 5 or 10 cents, which actually moves the needle on your total cost.
- Watch the Day of the Week: Historically, gas prices tend to be lower on Mondays and Tuesdays. Prices often creep up on Thursdays and Fridays as people prepare for weekend travel.
- Maintain Your Vehicle: A properly tuned engine and correctly inflated tires will save you more money over a year than finding the "cheapest" gas station in town. Fuel efficiency is the only real way to "lower" the price of gas for yourself.
The 9/10 of a cent is a weird, historical quirk that survived because of a mix of 1930s tax law and 21st-century psychological marketing. It’s a tiny reminder of how the "way we've always done things" can become an unbreakable rule, even when it no longer makes practical sense. Next time you're at the pump, just round up, pay the extra 13 cents, and know that you're participating in a century-old tradition of American retail theater.
Next Steps to Save at the Pump:
- Audit your tires: Check your tire pressure today; under-inflated tires can drop fuel economy by 0.2% for every 1 psi drop.
- Download a fuel tracker: Start using a crowdsourced gas app to find the actual lowest prices in your zip code rather than relying on street signs.
- Review your credit cards: Switch your gas purchases to a card that offers 3% or 5% back on fuel to effectively "delete" the tax and the fractional cent yourself.