Launching Event Handler brings you to the control center.
Click on the Bookkeeper icon to launch the invoice feature of Event Handler.
Use the file dialog to choose the Event Key to your event.
Add deductions, like donations, and select the folder containing all of Cashier's exported cash register data. With a push of a button Bookkeeper will generate a printable invoice for each vendor.
Add as many deductions as you want. Choose a percentage or $-amount per deduction and add to the deductions panel.
Select the folder where you've collected all Cashier data files from all laptops used as a POS device.
An invoice per vendor is generated. You will find a folder containing all invoices in the Cashier data folder in pdf-format. In addition Bookkeeper writes a CSV-file that can be imported into a spreadsheet, in case you want to data mine your event.