There currently isn't a setting for this and I don't think we'd be adding it as a feature.

The last I checked, I believe all credit card companies state it's against their terms of service to charge customers any additional fee based on the customer choosing to use a credit card for payment. This is to prevent businesses from punishing and discouraging customers from paying by credit card.

If you truly wish to implement this, you can still do it by implementing a custom payment provider/method.

https://hotcakescommerce....yment-Method-Example

https://hotcakescommerce....ment-Gateway-Project