Fee for paying with CC varies

[JonasKe]

So I chipped into a money pool in the UK (in GBP) and paid with my credit card without conversion.

For this Paypal charged a fee between 0.99-3.99 GBP depending on the amount.

After that I chipped into a money pool in the USA (in USD), also paid with my credit card without conversion.

For this there was no fee. Whatsoever. Nothing.

Which country/currency combinations result in a fee and which do not? Is there a list somewhere? I couldn't find anything.

[JonasKe]

Update: apparently the recipient in the states had to pay a fee for this. It did never specify this when I was send the payment. Is it always the receiver who has to pay in the states?