Check out 342.30(B)(3) and 344.30(B)(3). 20 verticle feet is allowed for both rigid and intermediate metal conduit if threaded couplings are used and support is provided at top and bottom.
Gondola? per Webster it is a barge, a balloon basket or a cable car. The NEC refers to industrial machinery or fixed equipment. I have never heard of the cashier's station being refered to as a gondola.....maybe in someone's imagination it resembles the Gondolas of Venice....Sing me a song, and push me along....