Is there a costing Unit of Measure other than the Primary in JDE?

We recently realized that there are issues in the system if the primary unit of measure is not the smallest transactional unit of measure.  We are trying to now follow that rule of thumb however we are now encountering an issue where the cost for the smallest UOM is smaller than the four decimal spaces allowed for capturing cost.  For example, we have an item that when you cost it in grams the value is $80/gm.  We typically use the material in microgram (ug) quantities.  If we make the primary unit of measure ug to match how we use it,