Choose the value for rounding subunits in Round Up When Subunit Reaches X Percent

Round up when subunit reaches X percent rolls the subunit level of an item up to a purchase unit and orders based on this percentage. An example would be 50%; when 5 packs are sold, it would order 1 carton. Another would be 80%; when 8 packs are sold, it would order 1 carton.