Single post in Changelog

Well, on Flight Rising, they have an auction house. They have a fee as well, but it's only taxed on the common currency (treasure), not the premium currency (gems). Something like that could be implemented, so that that way you aren't taking currency that the user likely paid for with their own money. (Maybe not with Gold Poke, though. Maybe there could just be a smaller 2% tax or so on that, and then no tax on Zophan since that is through real money only).