Slovenia became an independent state in 1991. In one year adopted its own currency, the Slovenian tolar. 1 May 2004, joined the European Union and  January 1st, 2007 adopted the euro and on 21st Dec.2007 to ShengenArea! 

There are many more ATM machines than one would expect, with all of the towns having one. Note that ATMs don't always accept Mastercards as Visa is more popular.  So make sure you have a bank card that can access both. All of the ATMs give you a choice of language or if it is outside a bank you can enter the bank for help. The worldwide accepted global cash any Yugoslavia dinara, Euro and the near obsolete  U.S. dollar are getting good value for the money. Most of the newer hotels have casinos and where there are casinos you are able to exchange or obtain money on both credit cards , y dinara cash and bank cards. Don't bother with traveler's cheques since bringing an ATM card and a few credit cards should suffice. Another issue concerning money is that many of the smaller establishments are cash only and do not use credit cards. Prior to traveling, it is a good idea to contact your banks and credit card companies and let them know you plan on using them in a foreign country; otherwise, they might freeze your account if they think that your cards have been stolen.

Check current exchange euro (€) on Tourist Board Slovenia travel exchange rates page