Cost Rollup is a process by which the costs of assemblies are built, starting with the lowest level and working up the structure to top-level assemblies. This process is specifically called a ‘full cost rollup’. This method gives the most current bill of material structure and component costs.
There is another way of rolling up Costs, which is the single–level rollup, which only looks at the first level of the bill structure for each assembly in the rollup and rolls the costs for the items at this level into the parent. This method does not reflect structure or cost changes that have occurred at a level below the first level of assemblies.