Technically, you're not supposed to pass on the 
credit card (Paypal) fees to the bidder because 
it's against ebay rules.  

However, it is fairly easy to get around this by 
a)charging a handling charge or b) increasing 
shipping or c) have a higher starting bid.  I do 
charge a handling chrage on all non USPS-IMOs 
because everything else is a pain in the behind--
I consider it an incentive for people to use the 
method that is easiest for me. Yep, I'm a big 
stinker I suppose. With the IMO, I go to the PO 
to mail it and pay for the shipping right there.  
Nothing comes out of my bank account, etc and 
whatever else is leftover either goes to cash 
bills (groceries) or back into the bank.  I try 
to charge as exact shipping as possible and I 
think my handling charge is reasonable.  Usually 
the handling charge only covers a portion of the 
Paypal fees anyway, so I don't feel as though I 
am ripping anyone off.