Press the second (from the left) purple button for Tip Adjust
You can retrieve a transaction in multiple ways.
Retrieve By:
Select the desired option and key-in the requested information and press Enter
The transaction will be displayed on the screen, verify it is the correct transaction and press F1 for Adj
Key-in the tip amount and press Enter
The screen will display Approved, press Enter to continue
To adjust additional tips, you can search through the transactions by using F2 for Prev or F3 for Next
When you are finished with all tip adjustments press the red (X) Cancel button until you return to the Payments screen