Tipping Scandinavia/Russia

[chris9757]

I'm getting conflicting information about tipping tour guides and drivers, as well as occasionally paying for the use of a public restroom in Scandinavia.  I really don't want to exchange for all these different currencies in these different countries, and try to keep up with the exchange rates.    One site told me tipping in euros is acceptable for this, although those countries don't use the euro.  What are the options for tipping?  Euro?  USD?  Other options?  We are using independent tour companies all the way.