But once you add the landing fees, handling fees, extra crew required over the year to operate one additional stop, hotels, per diems, catering and delays, 6 tonnes * US$ 550 is negligible.
Expect around US$ 30,000 to turn around a 380 in a major airport and once you include the extra crew salaries, per diems and hotel bills you are closer to $ 60,000.
The flight plans have a formula. On a 13 hour flight for every extra tonne of fuel / load you carry you burn around 500 KGS extra on the 380.