I think it gives you a price breakdown when you go through the transaction process. I would recommend holding off on booking South Point if you can. They've had two 50% off sales since January, and you can get a room
super cheap. I got a "Deluxe King Non Smoking City View" for six nights for $358.40 (including tax). $60 bucks a night was the more expensive room too. You could get the lower level rooms for $45, but I figured, "what the hell". It's my first time in Vegas!
There's no guarantees of another sale, but I would say that it is highly probable. In addition, I believe that you can get a full refund up until 3 days before your reservation, so you could always book your room now, and then amend the booking when/if the sale comes up.