Hi CottonMansion,
Since you posted this challenge sometime back, don't know if you figured out a solution or not. Also there's not enough info on how you have your events or items setup up. One work around would be to include a Service Charge which can be applied to individual items. Just something to look at. (Note, you would need to be using Square for Retail.) I believe that Automatic Gratuity is intended for Square for Restaurants.
