I moved in to campus affiliated housing at the end of August 09, but was required to pay rent for the whole month. My guarantor told me that the leasing office said the rent from last August would roll over to this August. Is that true? Is this what usually happens? I need to know because I'm running low on funds.

If you were living there for one day in August 2009 the landlord is entitled to rent for the month - unless your WRITTEN LEASE is to the contrary.

No, rent doesn't "automatically" roll over if you are not there for the entire month.