Yeah, for sure. You can get a
German Rail Pass which allows you anywhere from 4-10 travel days in a month for one price, which sounds appropriate for you. They have single prices and twin prices if you've got someone going with you, and they have the option between first class is standard class. Give it a look.
ETA: Wait, I may have misunderstood your question...are you looking for tickets that can be used in the Munich subway system? Or the "Underground Railway"? If so I might need to look further. I thought you were looking for multi-trips on the light rail.