Yes, they do, Ajailyn, and that's when you're charged a fee that's quite high if you use a card, not your PayPal balance or a bank account.
If you use your PayPal balance or bank account, there's no fee, but who wants to wait two days for a transfer from bank account to PayPal account...
I'm in the process of donating now. Just a warning - PayPal, at least in Norway, seems to no longer allow you to choose "Other" when donating, so you pay fees that are quite high if you are to transfer when you don't buy a service or an item.
The question then is how I and others who are going to donate in Euro can figure out what rate PayPal uses. I'm naturally converting from NOK to Euro, not from USD.