Gateway Fees allows you to charge customers additional fees depending on the payment method used to complete a purchase. The extension allows you to set a flat and or percentage fee for any enabled payment gateway. For example, if you wish to pass the credit card processing fee onto your customers, you could add a 2.9% + 30 fee to all purchases made through Stripe, PayPal Pro, Braintree, Authorize.net, or any of the other payment gateways that support direct credit card processing.