Here in Dallas it is 8.25% which is the same for each city in Texas. I have charged this for Texas residents due to the fact that you can pay fees if the person lives in the state that you have a facility.
I would suggest calling your local tax department in Houston and finding out what you need to put. If not you can get audited and that is not fun when you have to shell out profits.
Texas state sales tax is 6.25%. Each city can also charge up to 2.00% for a maximum effective sales tax rate of 8.25%.
As a host, you may be subject to property taxes if you have equipment and space in Texas. You will need to contact the local county appraisal district to find of the specifics. (Harris County Appraisal District if you are interested in Houston)