MRP Planned Order rouding value

Dear All,

I'm facing the next problem. I have  reservations  left from production orders that are partially complete because we cannot satisfy 100% the Production Orders (real life). In this case 11,962 kg. Because of them the MRP is creating automatically a planned order for 990 kg. (990 is the rounding value). I am looking a way to bypass them if they are smaller than a fixed value.