The prices shown in your store are the cash prices, and customers will see a service fee added to their receipt as a separate line item. To have the service fee discounted or cancelled out, all they have to do is pay using cash or debit card.
The great advantage of offering a cash discounting is reducing or eliminating card processing fees associated with accepting credit cards. If you don’t process cards, you don’t have to pay for the service.
Customers who pay with credit and debit cards do not receive the discount and will notice a non-cash adjustment on their receipt. This creates an opportunity to have more cash payments from your customers.
Since chargebacks originate from credit card payments, reducing such purchases through a cash discount program lessens associated risks, which could save you plenty.