Should Extended Stay rates replace additional dog rates?

I always book with the same sitter, and she charges $5 per additional dog. I have 5. This time I will be gone 5 days, which will be considered an extended stay. When I booked though it was significantly more than expected. When I looked at the details instead of saying additional dog $5 it said extended stay $28 under each additional dog. Is that normal? Also, I am not familiar with how rover works behind the scenes so to speak. Is this just how Rover charges, or is this how the sitter set up the rates?