You might check with your card company. I was informed we can’t charge a fee for using card BUT we can offer a cash discount. I know at one time, card companies restricted “adding fees” for using their card. Also, it’s my understanding selling as credit, seller eats the fee. Debit, bank eats fee. Not sure if that’s still true.I pay close attention to swipe fees some businesses try to make you pay them .Amex is 5%,mc and visa 2%. Most places in my area will not accept Amex , others here will charge you 3% to use a card.