Just had a chat with local bank and they say that Slovenia is still a restricted country in terms of currency,
This means that according to them, they will not buy back Tolar if you bring it home. Said as long as you take one of the three main currencies (sterling, euro and dollars) you should be okay.
Apparently the reason is that because the country is very small, the market for its currency is also small and therefore banks don't want to be bothered with it, as they won't make much money.