How to make an item from the cart complimentary?

Comp (a.k.a. complimentary) items are shown on the issued invoice with zero price with reason added as a note (e.g. Staff Dinner, Promotion, etc.).
Note that before you select comp reasons they must be created on the web dashboard first.

There are two ways to comp an item from the cart.

Comping via comp icon:

1. Tap on an item in the cart you wish to comp,
2. tap the comp button ('100%') on the bottom of the screen,
3. select the comp reason,
4. tap 'COMP'.

Alternatively, you can do that in the dialogue window:

1. Tap on an item in the cart you wish to comp,
2. tap 'EDIT' at the bottom of the screen,
3. tap the comp slider, it will move to the right,
4. tap 'SAVE'.

The price of a comp item in the cart is shown in strikethrough format and is not summed up to the total amount. The reason is displayed under each item.

In the example below, Full English Breakfast and Mint Tea items are complimentary, but Hot Chocolate is not.

See also how to comp an item from the open order.