Not sure but your best bet is to take the amount of the tax and put it aside and if it is included in your ticket then get yourself a nice meal if it isn't well then you were ready for it
Think what is written here makes super sense. You may, as others have noted, find the tax has been folded into the ticket price and is shown as a line item on your itinerary. BUT, what's your recourse if when you get to the airport they say it isn't for whatever reason?