To the best of my knowledge, the B1G regular season championship is shared by teams with identical records. Last year, Ohio State, Michigan State, and Michigan shared the title with 13-5 records.
The tiebreaker comes in to play with seeding in the B1G tournament. If we tie with MSU, we would be the #1 seed due to head-to-head. Here are the tiebreaker rules from last year's tournament:
http://www.bigten.org/sports/m-baskbl/spec-rel/111 011aae.html