Unlike craps and slots game, in Blackjack the decisions you make at the table have an effect on the house edge. In roulette the house edge is 5.26%. There are 38 numbers on the wheel and each spin is an independent event. In craps there are only 36 combinations of the dice. This never changes thus each roll of the dice is an independent event as well.
However some countries have placed restrictions on Internet gambling so you will need check with your local codes and regulations prior to play roulette.
How are the roulette sites able to give away free money and remain in business? The answer is simple. In most cases they get the entire bonus back and more. Casinos live by the odds that all casino games are in their favor and that eventually you’ll lose your original deposit and the bonus.