SAN ANTONIO - High gasoline prices equal lower sales at Riaz Vera??s two gasoline stations, the San Antonio Express reports. When pump prices soar, customers resist spending money inside the store, which means profits are squeezed even tighter.

In San Antonio, gasoline retail prices jumped 29 percent in the last 12 months, which correlated in a sales drop of around 20 percent for gasoline at Vera??s stations. Inside sales plummeted by around 25 percent during the same time period.

Independent retailers like Vera aren??t the only ones suffering, though. The Valero chain has redesigned stores and closed underperforming stations in recent years. "It's just a very competitive business," said Bill Day, Valero spokesman. "These (gasoline) sales are often a break-even proposition at best."

A gallon of gasoline is marked up on average around 16 cents, said Jeff Lenard, NACS spokesman. Out of that 16 cents, a retailer pays bills and taxes, leaving around a 2 to 3 penny profit. If a retailer sells around 4,000 gallons of gasoline a day ?" the average ?" that means he makes around $100 daily profit on gasoline.

"About 70 percent of sales dollars come from gas. But only 26 percent of their profit dollars come from gas," said Lenard. "Gas is a traffic driver and gets (customers) to the lot. But it's inside the store where you run your business."

Larger stations that are owned by fuel companies can often negotiate better deals on fuel and sell that gasoline cheaper than independent retailers, said Day. Those lower prices can drive in-store sales, which in turn increases profit margins.