jadbreen

Did anyone ever find a solution to this? I've spent hours trying to figure this out and haven't had any luck.

I, too, would like to know the solution!

I purchased the Add a Tip plug-in from Thompson Web Design--recommended by paul2009 above--and modified text so people could add an optional donation at the time they purchased a ticket for a virtual musical event.  I had some challenges setting it up and Bradley Thompson was extremely helpful, responding promptly to e-mails.  If you're selling a service product--and don't have to contend with the tax issues mentioned by aladdinsane--I recommend the plug-in.