As it is customary to tip in many countries all over the world, it is important to have the option in your PoS interface.
To activate the Tips feature, go to `Point of Sale --> Configuration --> Point of sale` and select your PoS.
In Payments category, you will find Tips. Select it and create a Tip Product such as Tips in this case.
Add Tips to the bill
Once on the payment interface, you now have a new Tip button
Add the tip your customer wants to leave and process to the payment.