All bets * (1-.981).  That is roughly how much the house is expected to rake.

Think of SatoshiDice as a laundrer, it returns you 98% (roughly) of your money over time.  Now some people play wierdly trying to "beat the numbers" and they might actually lose 100% of their money.  That sweetens Satoshi's profits.  But as Dooglus has shown, pretty much it's just laundering and taking a 1.9% fee.