I would say that units in cover do not receive a penalty to their shooting.
Quote:
1.8.2
Units that are in terrain that is tall enough to at least partially
obscure them from an attacker’s view receive a -1 to hit
modifier when being shot at (see 1.9.5). The to hit modifier
also applies if intervening terrain obscures the target partially
from view.
The first sentence means that shots against a target that is in a terrain feature that obscures the target from the attacker suffer a -1 to hit modifier. It thus doesn't penalize units in cover: it relies on what terrain features the target is in, not the attacker. The only circumstance where it might come up is if the target is in the same terrain piece as the attacker.
The second sentence then comes into play. The question becomes whether a terrain feature an attacker occupies is considered intervening terrain when that attacker shoots (since intervening obscuring terrain can also provide the penalty).
1.8.3 tells us that infantry gets a -1 whenever in cover, but I'm not sure it's talking about when
they shoot. I think it's talking about when they get shot
at (remember that 1.8.2 phrases it in terms of the target getting the penalty to be shot at, not the attacker getting a penalty to shooting). So you again end up at the question of whether terrain you're in is intervening.
I would, generally, not consider it such, but it'd depend on the terrain feature in question and the positions of the units involved.
