Found out that selling an item for 4 Robux earns you 3 Robux, for some reason.
Then I thought, maybe they take less than they actually should because the 30% tax is closer to the lower option (25%) than the higher option, (50%) and I was right. For example, selling your item for 31 Robux would earn you 21.7 Robux if Rocents were a thing, but it earns you 22 Robux (around 29% tax) with Roblox’s tax system.
I don’t know whether it has been always like that, but it looks like the tax is rounded to the nearest value rather than the highest now.
Looks like it isn’t anymore.