That I am aware, all of the bonuses come at 100.0 skill, and these are mostly for the combat skills. There used to be a time where skills had even breaking points. For instance, you used to get 1 MR per 10 skill in meditation. So then having 120 vs 119.9 really did have a difference. In most, if not all, cases this was done away with years ago.
There are still some reasons to have 100.0 in a crafting skill vs 99.9 if you want to mark exceptional items/display a certain title.
In general though, I agree with Corwin that there's no measurable difference between 119.9 and 120 in skills like tactics/anat/resist. Chiv I think there is a threashold at 120 to get the last small piece of bonuses on your DF.