I think ive already suggested a proper fix for this earlier in the thread; make the multiplier based off of the winning chance: multiplier = 0.992/(win chance)
right now, the win chance being dependent on the multiplier is causing the rounding issues.
Exactly this. There are 10k different possible rolls (or 100k, for now, etc.) so have the roll target and the stake be the things which define the bet, and have the payout multiplier be derived from that (and calculated to enough places that the rounding doesn't matter).