I pay for the credit card processing fee for the item part of the bill. For example, if someone came in and bought coffee for $20 and left a $10 tip. My credit

I pay for the credit card processing fee for the item part of the bill. For example, if someone came in and bought coffee for $20 and left a $10 tip. My credit card fee is $0.66 (2.2% of the $20 which is $0.44 and 2.2% of the $10 which is $0.22). So out of the $10 tip the wait staff gets $9.78 ($10 - $0.22).