What to do when you are a finalist for a tenure-track position but you want to wait until you complete interviews at other schools? I visited a school for a tenure track position and the chair informed me that I am a finalist for that position. While, I still have interviews at other schools remaining, other candidates seem to have finished their interviews. 

The chair asked me whether I would take an offer before visiting other schools but they did not give me an offer yet. Is this common?
Does the fact that other applicants have finished interviews affect the school's decisions?
After serving and chairing search committees, I agree with Brian that gamesmanship is often central to the faculty search process. The other candidates for School A may have finished interviewing (assuming that you are correct - how do you know the other candidates' schedules?) but now School A has to make the offer to the candidate they like best AND will say yes. So, they are putting pressure on you. 

Personally, I feel like the response can be simple. Your question implies that the chair is telling you that you're probably going to get an offer, but do not have one in hand. So, you can tell the chair, "I would be willing to cancel other interviews for an offer IF it's the right offer. If you draft an offer, I will look at it and decide if I can accept it without pursuing other opportunities." This is VERY important, because you legally do not have an offer until they send you one in black and white. Once you have an offer, if you are satisfied with it and like the department, then it may be easy to make the decision. 

In my first academic position, I was told that an offer would be sent to me and there was an administrative hold up...for two weeks or more (this was several years ago). I called the chair and told him that I was going to go to other interviews before I have their offer in hand. GOOD LUCK!