First, check that passing the credit card processing fees on to the customer is legal in your state as in many states it is not legal.
You can simply add a line item that says credit card fee or something to that effect.
Personally, I would recommend you try and build the credit card fee into your prices just as you build rent, insurance, labor, property taxes, and utilities into your prices. Customers don't want to feel nickel and dimed, nor do I.
