This concept should be installed in QB, it’s very simple.

$300.00 invoice to a customer

QuickBooks:

Do you want to pay this invoice online $300.00

Customer:

Yes

QuickBooks:

Select pay with credit card

All credit card transactions will incur a 3.5% fee

Total Charges for this transaction: $310.05

Do you accept this charge

Customer:

Yes

QuickBooks:

Click to pay this invoice in full

Pay this invoice of $310.05