It's well known that all payments should go through the "goods and services" tab, after all they are paying for a service from you. But there's been a recent viewpoint that the commissioners are the ones who need to pick up for the 2.9% tax they put on each tab. And through a bit of talking around, I've come to the conclusion that's illegal, well morso against the terms of service on Paypal.
In layman's terms, if your selling your services, your responsible for all the fee's for using the service for getting the money in the first place. Though I suppose you could re-adjust your prices through your commission sheet, I can imagine how annoying it would be to redraw those prices every time the tax went up.