OPM Cost rollup displays Material Cost of final level at Lower Level.

After cost rollup for a product, if product is manufctured in three levels, Lower Level shows Material Cost of all three levels. In this level(i.e.in third level) only  Resource cost of third level gets displayed. Is it right for the Business Process? If Business requires Material cost of Third Level, how it can be findout? Oracle claims this as standard functionality. How can we get third level material cost based on component class wise? The impact is we can not calculate the cost of a specific level of production.How can we find out cost only for specific level of production?