The CC company can pull the access to the system if you violate this rule.
CC companies Charge $0.30 per transaction plus from 2.0% to 5%.
This rates very depending on the company and also the type of card. Reward/ Airline miles I have to pay a higher percentage than a debit card. NO THE REWARDS AMD AIRLINE MILES ARE NOT FREE.
Myself and many SB owner will not take American Express as the gorge us on the fees.
The Credit Card companies prohibit charging any fees in addition to the sales price total of the charge.
There are a number of businesses who get around that part of the merchant agreement by offering a discount on cash payments.