here is our current design of Mobile Point of Sale (MPOS) UI for the Gratuity (leaving tips if simple). MPOS is that device that you see mostly in supermarket when paying by card (small screen, card reader, buttons for up-down navigation, buttons for PIN entry). Like this:
Here we are adding UI screen/page to be able to leave tips also, e.g. at restaurant
So customer has small device before him, list of elements is displayed as described below (example1), first item is selected by default (highlighted), user can navigate up/down using arrow buttons, user can press "green OK" button to select item
The dilemma is:
If "No tip" is selected by default (example 1), then many customers will simply press OK and proceed without leaving tips. That is bad for the merchant (less tips)
If some percentage is selected by default (example 2), then some customers will simply press OK and leave tips unintentionally. That is bad for the customer
If some "unclickable" line is added to the first line (example 3) to force customer make explicit deliberate decision, then it will be probably bad for User Experience, because up-down navigation will be required. But this can be good for the merchant, probably more tips
Example 1, "no tip" by default
No tip (highlighted)
10%, <calculated amount>
15%, <calculated amount>
20%, <calculated amount>
Custom tip amount
Example 2, percentage selected by default
No tip
10%, <calculated amount> (highlighted)
15%, <calculated amount>
20%, <calculated amount>
Custom tip amount
Example 3, non-clickable item by default
<...> (highlighted)
No tip
10%, <calculated amount>
15%, <calculated amount>
20%, <calculated amount>
Custom tip amount
What are your thoughts regarding this?