managing fractions of quantities on BoMs

What is the best way to list quantities on a BoM when only a fraction is being used. 

Example.  Wire     UoM  = inch  but we only require a 1/2 inch  (.5)       WO qty = 21   required qty would be   10.5   amount reflected to be issued is 11.

We're finding the quantities round on the issues, MRP requirements, Supply and demand.   The round to whole number field in the Item master is blank.   We use to show these items on the BoM with a qty = AR but a request has come in to include these quantities so we could be better prepared, for any spike orders as MRP would pick up on the increased demand (which we currently would not see because we work off safety stock for these items) and pick them up for our costing purposes.