First of all, you should check the state laws to see this is even legal in your state for charging a surcharge to your customers for using a debit/credit card, they vary from state to state. It’s also as part of the Intuit Payments Merchant Agreement.
Refer to #3 No Surcharge part of Merchant Agreement document:
“3. No Surcharge. You agree not to charge your customers increased fees, surcharges, or any other premiums for a Gift Card transaction, for a customer’s use of a POS terminal, or for the operation of the system unless such surcharges are permitted by applicable laws or regulations.”
Also, cash discounts are NOT legal in many states.