Thanks! I guess I still don't know how those work either and don't see anything about jackpots in the FAQ. Oh well.
From The main page:
Looking here:
http://satoshiroulette.com/game-info.php?game=roulette-00&mode=TRC
We see that landing on 0 pays your bet x 36.
(10 TRC x 36 payout multiplier) + Jackpot of 77.54125968 TRC = 437.54125968 TRC.
Assuming a full round is played with all results occurring once we also need to factor in the jackpot donations of 1%
(36 losing results x max bet 10) * 0.01 = 0.36.
437.54125968 + 0.36 = 437.90125968 TRC
Total Bets for a round 37 * 10 TRC = 370 TRC
Total rounds payout 437.90125968 TRC / 370 TRC = 1.1835169180540540541
1.1835169180540540541 * 100 = 118.35%