You've ordered drinks at the bar, and now it's time to pay. Before you even see the total, the bartender hands you a tablet with a digital tip screen. The typical options are 18%, 20%, 25% — or ...

You had dinner at a restaurant and the check has just landed on your table. How much you’ll tip probably seems intuitive: between 18% to 25% of your final bill, depending on the quality of service you ...