Overtender

There are certain situations when a customer may want to pay more than the Amount Due on a transaction. Prism enables you to control this on a tender-by-tender basis by editing the Max Over Tender field in Admin Console > Node Preferences > Transactions > Tenders > Requirements.
Here are a few common situations in which a retailer may want to allow over tender.
Check: a customer may write a check for more than the amount due and receive the change as cash. Think of a customer that the retailer knows well and who needs some small amount of cash to be used later for parking, dinner, etc.
Debit Card: A common practice with Debit Cards is to allow the customer to receive some amount of "cash back" in addition to paying for the purchase. The cash back amount is added to the purchase amount and the total is deducted from the customer's account.
Credit Card: Typically a credit card transaction is always for the Amount Due; however, depending on the retailer and the local regulations, over tender of credit card may be allowed. 

Default Max Over Tender Amounts
The following table lists the default Max Over Tender Amount for each currency.