Enter the total bill amount via the on-screen keypad, select the tax % from the list (or allow SplitBill to calculate it for you based on the $ amount) and assign the tip %. The Tip calculation may be made either before or after tax. Enter the total bill amount via the on-screen keypad, select the tax % from the list (or allow SplitBill to calculate it for you based on the $ amount) and assign the tip %. The Tip calculation may be made either before or after tax. SplitBill takes the guesswork out of splitting/calculating a bill among a group (or individual). Use the Tip Wizard to apply a logical approach to tipping. Simply answer a series of questions about the service received and let SplitBill calculate the tip % for your server. Additional tools such as a service timer and Tip reference are available to make using SplitBill a pleasure.