isn't this exactly what microsoft did "last gen" with microsoft points?
i also see this in every F2P ever... always buy an even amount of fantasy currency (e.g. 4000 crystals) for lots of real money and the ingame prices are uneven all the time (e.g. 3957 crystals for a shiny hat). this way players loose the sight of how much money they spent, because fake currency is pretty high numbers, and after a purchase they have a small amount of fake currency left, and its just a bit too less to buy a new shiny thing (which will cost you like 57 crystals and after the shiny hat you have only 43 crystals left) , so you purchase more fake currency and then it's welcome in the loop