You can now create add ons that have dynamic pricing based on the overall cost of the item being purchased. Starting today you can set a percentage-based add on pricing option.
As an example if you offer a $100 activity and the customer buys a 10% gratuity add on that add on will cost $10 and the total of that participant will be $110. Percentage-based add on pricing is perfect for gratuities and can still be charged taxes and fees like any other add on.