When there is no incentive to mess with the hash, it may be safe to rely on the last digit. But as was said here (and DH above previously) when there is incentive to do so, it is possible to do so.
Recently,
www.bitcoinbetting.website made the following announcement...
Maximum bet amount allowed has been raised from 0.1 BTC to 1 BTC. Anything over this amount will be considered as donation.
So, the winning amount, i.e. 16 BTC, is more than a block reward, i.e. 12.5 BTC. Do u think, miners may hold a block now if they place 1 BTC bet with a wrong choice? Appears impossible to me...