Offering a discount or adding a fee to a specific payment method is as easy as modifying the payment method in question. Here's how to do so:
Go to your store's payment settings
For the payment method in question, click its name so its respective modal appears.
Enter the discount or fee in the "Discount or fee" input field, then click the "Save" button to the right of the input field.
- To add a discount, enter a positive value. For example, for a 10% discount, enter: 10
- To add a fee, enter a negative value. For example, for a 5% fee, enter: -5
That's all done! The payment method in question will now have a fee/discount applied, which will be visible to the end-user during the checkout process.