Most scopes of 10x or under don't have enough parallax to worry about when big game hunting. In fact most of 'em work fine for varmint shooting.
But you should always test a new scope for parallax anyway. the most I've found in a 6x is about 2" at 400, which means a possible inch of aiming error--if you don't have your eye directly behind the center of the scope. But I have found considerably more in some 3-9x or 3-10x scopes, and they should all be tested.
With a 6x I generally hold off for windage, but do know some people who crank it in.
