If you use our CC system, our fees are a flat 3.5% + .30/transaction. We don’t charge differently for Amex vs. MC/Visa/Discover. We also don’t charge you if you don’t run any transactions through us. We offer our payment system as a convenience to you and your guests. With our system, your guests can put a card on file and pay directly from their phones. No lines to capture cards at the end! Trust us, that convenience is worth the half-percent you intend to save using another processor like Paypal or Square.