For some reason I thought the word literally meant "campaigning."
It does, it means operation (like a military operation, I posted this above). Etymologically, it comes from the same root as the Hebrew word Bitzua (ביצוע) which means fulfilling, doing, acting on etc.
AFAIK, "mivtza" in Hebrew means either "offer" or "operation", not "sale".
This is quite interesting, the word Mivtza as in sale may have a different etymological root, maybe it comes from the word betza (בצע) which means money, or like b'tzia (בציעה) as in breaking bread.