Or maybe skip the fancy UIs and recommend paying cash for tips?
As someone who's worked service jobs in my youth, I'd really like to stress the importance of cash over CC tips.
Pay is usually abysmal and CC tips don't always make it into the pockets of the people who deserve it, not to mention the delay.
Also, cash is easier to split when necessary. For example, between the wait staff and the kitchen staff.
So please always tip in cash.