Many gambling casinos right now is giving a good RTP to their games because this courage a lot of members or players to play in their gambling casino, also regarding the exact algorithm or variable with it because this is confidential with the database connection, but still, there's information in the internet that could be used as references to the RTP of the casino.
there are casinos that publish this data, also often can be found in games rules and there other sometimes peculiar methods, for example:
Book of Dead, playngo:
Stake - 96%
Roobet - 94%
Duelbits - 96%
Bitcasino - 96%
Winz - 96%
Betfury - 96%
Punt - 96%