Last year, when food prices rose along with so many other costs, José Theoktisto began to think about how to lower operating expenses at the Venezuelan restaurant he runs in upstate New York. He worked with different suppliers, and he raised menu prices. Then he took a closer look at his statements and found that he was paying $2,000 a month in credit card fees.

“They pile fees on top of fees, on top of fees,” Mr. Theoktisto said about credit card processing companies. He said that he normally pays 4 percent per transaction when someone uses an electronic payment method, but that he also has to cover other charges related to credit cards, like a fee for when a customer uses a card from another country.

In January, he decided that instead of raising prices, he would add a 4 percent convenience fee to the bills of customers who pay by credit card. He is just one of an increasing number of restaurant owners adopting these policies as inflation cuts into his bottom line and credit card fees rise.

Mr. Theoktisto said that since he and his wife opened Oh Corn! Arepas about seven years ago near Troy, N.Y., the number of customers using electronic payments has increased from 50 percent to 90 percent. He is not alone.

“No one’s using cash,” said John Horne, the owner of Café L’Europe and several locations of the Anna Maria Oyster Bar in Sarasota, Fla. He said he has paid about $279,000 in credit card fees this year among his six restaurants, and is thinking about adding a broader service fee. “It is increasing the cost of doing business in every industry. And the consumer doesn’t realize it.”

For many diners, though, the restaurant check is starting to resemble a CVS receipt. The credit card fee charge can come on top of the tip and various service charges that many restaurants now impose on customers. Michael Thompson, who owns a restaurant, a food truck and a truck stop in Klamath Falls, Ore., said he recently ate with his wife at a Mexican restaurant downtown and found a 3.8 percent credit card fee on his bill.

“It really bothered me,” Mr. Thompson said. “I’ll never go back.” He said he’d never charge these fees at his establishments.