It would be convenient if it were possible to optionally include rounding the amount of the required item to the stack. When sending something through a Space Exploration rocket, there is a percentage of loss of items, so accurate loading into the rocket may not be effective

I think it would be better to have a separate mod/entity, e.g "stack rounder", as this is not really related to the functionality of this mod.
That would also allow other applications, for example rounding after rocket loss multiplier, and keep this mod simple.

Actually, there seems to already be a mod like that, Stack Combinator (https://mods.factorio.com/mod/stack-combinator).
It seems to do exactly that, but I have not tested it.

Actually, there seems to already be a mod like that, Stack Combinator (https://mods.factorio.com/mod/stack-combinator).
It seems to do exactly that, but I have not tested it.

Yes, there really is such a mod and I sometimes use it, but in terms of combining with your mod, it will be an additional element, plus it has its limitations

If there is an external solution I will work on other things first, maybe I will add it if there is nothing else to do.

This mod https://mods.factorio.com/mod/GhostScanner2 has this function