If you pre-pay for a service and the tax rates go up, can you be charged an increase?

I pre-paid for a hotel room a year in advance. On check-out they charged me an additional fee for the increase in hotel and lodging tax. Since the rate increased.

I got them to remove the charge when I noticed it, but questioned the legality of this in the US.

Anyone with experience on how taxes and pre-paid items/services work?

 

I don't know,first time I hear about something like that.