How to add % charge for PayPal when you checkout on a Wix store.

Is there a way to code in a percentage charge when a customer chooses PayPal as their method of payment.

For example when a customer is at the checkout of the Wix store and selects PayPal we want it to add 5% to the total and it shows it in brackets the charge so the customer is aware of this charge when selecting PayPal.

I have seen it on other web stores. But likely not to be WIX but thought Id ask incase anyone knew a way to do it by code etc???