I don't even use Krita, but donated €15 anyway, just because I know what it's like to deal with the utter shitstains at the VAT department of the Dutch tax service.
As someone who recently paid 200€ in fines to another EU tax authority over 150€ in income, of which I was exempt, just for marking the wrong box, I can sympathize. Just made a small donation.
SEPA transfers are usually free for personal accounts, be it sending or recieving, but business accounts usually charge a < 10 cent fee for recieving a transaction.
But if your country doesn't use the Euro (i.e. the UK), domestic Euro transactions can be more expensive than domestic transactions in the home currency.