I typically sight in to be .25" or so low at 25 yards. Usually if you are dead on at 25 yards then you will end up way too high at 100. Depending on the speed of the bullet and distance between the centerline of the bore and the centerline of the scope I have seen them up to 8" high at 100 after being sighted dead on at 25. Now as Tyler stated, if your barrel is perfectly level then your bullet will not rise. Don't worry, no one shoots with the barrel level, they are always angled up slightly and the bullet will always rise because of this, well until gravity overcomes momentum and it starts to drop.

I would get get closer to zero at 50 than 2" low. If your centerline difference is 2" or less, you will actually be lower at 100 than you are at 50. I would give it 8-12 clicks up before I shot at 100.