Originally Posted by UnitedSkies

There is a uniform 7.5% U.S. Transportation tax (code is US).

I'm not sure if it's technically a sales tax.

From a recent article:

Ticket taxes

A 7.5% federal levy is attached to every plane ticket. These are collected by the airlines and passed along to the Internal Revenue Service, which deposits them in the Airport and Airway Trust Fund. A separate Rural Airport Tax of 7.5% is assessed on flights that begin or end at rural airports, but those passengers then are exempt from the other ticket tax and the segment tax. Passengers traveling between the continental United States and Alaska or Hawaii pay an additional $7.50 in taxes. Over the past decade, $49.6 billion has been collected in ticket taxes.