Order Multiple for family of parts

Hello all,

I am procure about a dozen different materials for which all require the same capacity for transportation. I may have different material mixes on different days. I would like for the sum of calculated requirements to total a certain number of units thus allowing me to utilize my transportation resources more effectively.

Is it possible to create an order multiple or rounding value for a family of combined parts? I would like the sum their daily requirements to total a multiple of a fixed value.