You can solve this with the Payment Gateway Based Fees extension. We use that extension for this exact purpose. It allows you to charge a set fee or a percentage-based fee for each of your payment gateways. We have it set only for our credit card gateway with a percentage-based fee.
You can solve this with the Payment Gateway Based Fees extension. We use that extension for this exact purpose. It allows you to charge a set fee or a percentage-based fee for each of your payment gateways. We have it set only for our credit card gateway with a percentage-based fee.