From my understanding, this isn't a thing for GradHouse. The handbook says it's preferred that you don't have guests for over 3 consecutive nights or over 9 days within a given month, but it is not a hard and fast rule (http://gradhouse.utoronto.ca/residents/policies/, pg. 22). Roughly speaking, try keep your over night shenanigans to the weekend. Also, I don't remember there being any sign-in policy for guests when I was around there last year with some people. It isn't designed for undergrads, so they kind of assume that you are responsible.
EDIT:
Oh, and the $55/85 guest rooms are just so that if your mom wants to stay in the building but you don't want to sleep with her. I mean, i don't know, I don't judge.