I know it is a pain, but occupancy tax is not a sales tax and should not be included in that computation.
what would happen if the room charges food or drink or ... you would be charging occupancy tax in addition to retail sales tax on everything.
Occupancy tax should be set up somewhat like @Angelyn_T suggest, but as a line item you use on the invoice
use a service item
set the rate as a decimal representation of the sales tax amount
on the invoice use the amount to be taxed as the qty