Has anybody set up their ERPNext instance to support Cash Discounts/”Dual Pricing” whereby an item has a “Credit Card” price and a “Cash/non-credit card” price?
You can try a different Price List for Card or Cash, and apply the pricing rule accordingly for a discount.
As @ERPNextSafari said you can try that if you have few items
Alternatively if you have many items - in the selling menu under items and pricing there is a doctype called pricing rule
E.g. you can apply a 8% discount on a customer group called “Cash Customers”