Is there a standard amount to deduct from the rent paid on a room when the house is being sold and the renter must make many accommodations such as being out of the house at specific times?

There are no "standard" deductions, but that doesn't mean you aren't owed some sort of consideration. What are the terms of your lease? Does it say you have to be out of the place during showings? If not, you may have some leverage to get a rent reduction for your inconvenience.