During the payment process, you can calculate the amount of change you need to give a customer.
Here you can see the total amount of the invoice.
In the field "Given" you can enter the amount received.
If the customer/guest wants to give you a tip, you can enter this here. Leave this field at 0,00€ if you didn't get a tip.
Here you can see the amount to be paid, including tips, as well as the amount of change.