What happens if the deciding state in an election is tied

[Vosem]

Well, the specifically Wisconsin law is that elections determined to be tied are determined by a coin flip; this has happened at the small-town level.

A statewide election would never be determined to be tied, though. After protracted court wrangling about what to do with individual votes, someone's lawyers would triumph and that candidate would be declared the winner. If this would take longer than it takes for the Electoral College to meet, the state legislature has the authority to appoint electors itself (which in Wisconsin at present would mean a Republican victory, but could be a Democratic one elsewhere) or, if it is deadlocked and cannot send a delegation to the Electoral College, with no majority the election would be thrown to the House.