The banks are making merchants pay for cash back rewards, air miles, and other perks given to cardholders for their credit card purchases. They advertise these benefits knowing they aren't going to pay for them, but they are going to make merchants foot the bill. Perfectly legal and allowable, you can now encourage your customers to pay by debit card with no extra cost.
However, if they pay by credit card the machine will automatically add 3.00% to cover the costs of accepting their card. We put this fee towards your credit card processing costs. This leaves you with significant bottom line savings every single month.