From the Virtual Terminal
Merchant login to Virtual Terminal;
On Control Panel, click on “Find Transactions”, then click on “Credit”;
On the “Transactions Filter” box/window, click on “Submit” on the bottom;
Locate the transaction to be adjusted from the list and click on its “Ref #” (1st column);
Scroll down to the “Receipt” box;
On the right next to the receipt the “Adjustment” box will appear;
Enter the TIP amount and click “Yes, Adjust Transaction”.