As an artist that relies on commissions as my income, I absolutely do not charge my patrons for the PayPal fee. While yes, a dollar or two here and there add up over time, I have found that people are much more willing to buy when you have nice even pricing, as opposed to saying, "X item is 22.91" or whatever.

The fees are really not that much, and honestly if you don't want to pay to use the service then how can you justify having other people pay you for your service. Especially if Paypal is the only payment method that you accept.