First, you need to enable the option to add tips in Sapaad:

Step 1: Visit Setup > Global Settings > Others.

Step 2: Enable the Accept Tips option.

To add tips for an order:

Step 1: Go to your Dine-In screen and click on Completed Orders.
Step 2: Click on the order number for which you want to add tips.
Step 3: Click on the + Tips button, enter the tip amount and click Add.