This is a basic principle of Betcoin, so please understand this clearly. First, the casino, poker room and sportsbook are not in $, they are in bitcoin. When you play in poker tournaments you have the option of using bitcoin to buy in to shared tournaments where the buyin is in $. When you do this you are using your bitcoins to pay in dollars at the current market rate which right now is 1 btc = $323. Since the casino is in 1 btc = 1,000 credits. Therefore when you buy in to a tournament that costs $5.50 you pay 17 mbtc or 0.017 and win you win $5,000 you get 15,420 credits. Is this clear?