This depends on the country you live in, but in New Zealand the tax on gambling profits is regulated by the Lottery Tax ACT (552/1922) and the NZ Income Tax Act (1535/1992), while the gambling law is administered by the Department of Internal Affairs (DIA).
But you as an individual from New Zealand after winning a casino no matter the amount, are not required to pay taxes or report your winnings. Also if you choose to play at bitcoin casino NZ sites, you are not required to report any winnings.