my experience is: these taxes will be automatically raised and collected as soon as your itinerary identifies a stopover of more than 24 hrs as it is assumed that for a shorter (transit) period one would not leave the transit area. But if you do it - and I did it for a couple of hours upon my transit time of approx 5 hrs - they check your ticket very carefully upon reentering the transit area if this tax has been raised together with the fare in the ticket. As this is usually not the case they do collect it locally and this can hardly be avoided. But honestly: I think its worth leaving the terminal and go out and even to town for a couple of hours.....