You’ve played a great show. Fans are lined up at your merch booth. You’re taking cash, making change, and signing CDs. Then a guy walks up and wants to buy a couple discs and a t-shirt — but he only has a credit card. Are you going to turn him away? No, you’re going to process his credit card transaction right then and there, in the sweet, dank, dark-lit, beer-soaked corner of a basement rock club.