Let me clarify this topic:

Mexican citizens are not subject to the Mexico Tourism Tax when traveling to Mexico. This is usually identified with code UK in the reservation system. Again it stands for Mexico Tourism Tax.

To get the taxes taken out from the total ticket price, call Continental when making the reservation (if doing this over the phone) or Continental.com Support right after you make the reservation. Request to have this tax removed. The agent will ask if the passenger is a Mexican citizen, and substract the tax from the total amount. It is usually around US $20.

It is a pretty simple procedure that most Continental agents are very familiar with.