If you need this automated and right away, one option would be to contact one of the developers listed here for a quote on the development of a custom built add-on for this purpose:
The support post ‘gst add on’ is closed to new replies.
Have a question about this support post? Create a new support post in our support forums and include a link to this existing support post so we can help you.
Support forum for Event Espresso 3 and Event Espresso 4.