Bid whatever you want. The room count in many MLS services often includes finished basements, that may be the issue here. If you walked the house then you know if it works for you - what they call a room makes no difference.

If you want to see more on this very issue - http://www.hrmiller.com/is-it-a-br-or-den.asp

Hank

You may submit an offer for any amount you wish and for whatever reason you wish. Likewise, The Seller is free to accept or reject any offer. I would make sure that any offer is contingent upon an Appraisal. The appraiser will take into consideration the number of rooms and square footage of the property to assess the value of this house. If you are obtaining a mortgage loan for the purchase of this house, then your lender will most likely perform an appraisal as the amount they are willing to loan to you is dependent upon the appraised value of the property.