Steps

• Add Items - scan, enter item id of any sort or use the quick pick panel to add items to your transaction.
• (optional) Add customer 
• (optional) Apply Discounts or package prices.
• Take Payment - click pay.
• Select the first tender type, enter the amount for that tender and select done.
• Select the second tender type, select done and the receipt will print.

Settings That Affect This

• Store Operations >> System >> Manage Registers contains the list of valid payment types for a given register. Some payment types can be disabled for instance if a certain register does not take credit cards or cash.