NASHVILLE, Tenn. -- As Tennessee's average gas price continues to break records, some people could be unknowingly paying more than others.

Related: Special Section: Gas Prices | Video

Tennessee's average price currently stands at $3.66 a gallon.

Depending on where customers pump, drivers could be paying a little more at some gas stations and not even know it.

The practice is called dual pricing, and it's something people need to know before they choose where to fill up.

While the fact is surprising to some people, gas station owners don’t make a lot of their money on gas sales.

Joe Moss owns a small station in Chapel Hill. One of his gas grades is selling for $3.70 a gallon.

Of that price, about 40 cents goes to state and federal tax and $3.24 goes to supply costs, which leaves Moss with 6 cents for profit.

"It's harder to make a dollar than it used to be," he said.

But Moss said things get worse because credit companies get to take around 7 cents on the gallon.

He said because gas prices are so high, more people are using debit or credit cards instead of cash to put off paying for it right away, which leaves him 1 cent per gallon in the hole.

To save his business, he said, he's turning to something a lot of independently owned stations will have to do: cash versus credit. Paying with cash gets drivers cheaper gas, and the convenience of swiping a card will cost drivers at least a nickel more.