Cutting off the tips of roof sheathing cap and metal screws so they don't show?
The portion of a screw sticking out into space doesn't have anything to hold onto, so it's not doing any good. Once the wood has been compromised enough for the threads to pull out, additional threads will just pull through the larger hole.
A nail, OTOH, will continue to provide friction resisting pull-out for its entire length, as the hole generally isn't enlarged much due to &quot;natural&quot; causes pulling it out (as opposed to being broken up during intentional removal). This can be proved by trying to pull a 3&quot; nail - it takes nearly as much effort to get the last inch out as it does the first inch.
This is a long winded way of saying &quot;go to town cutting them off&quot;.
Also, if you take the time to measure where the joists are and snap chalk lines on your roofing, you'll have about a 99.99% chance of getting every screw into a joist, so you won't have anything to worry about in the first place. Getting the screws right up front will probably take less time than cutting off the ends later anyway.