8 year old a really bad loser

[Tommy]

DS3 is becoming increasingly whiney when things are not going his way and it's driving the rest of us crazy!
If we are playing Monopoly say and he has to pay rent, or someone jumps in on another game and takes his chance or whatever it is, he throws a tantrum reminiscent of his toddler years and cries.
He's always been a bit of a whiner but I think we were hoping he would have grown out of it by now. I know he's not like it at school - any tips or advice?