Here’s the basics of split tender with Gift Cards and Store Credits ..
Add some stuff to the receipt …
Hit Pay
Select Gift Card (or Store Credit) enter the gift card number or credit
Enter the amount to apply to this transaction (maximum is amount of transaction) (see enclosed image)
Click Done
Click Credit Card
Run your card (I assume you have something on the counter that actually runs the credit card transactions
Back on the payment screen
select Card Type (see enclosed image)
enter approval code (optional)
click Done
Receipt Print Preview Show up
Click Print