how does standard cost for top level item in BOM get rolled up

Summary:

My end users want to know how the standard cost for a top level item in a BOM gets calculated. We need details of how standard cost gets applied at every BOM level.

Content (please ensure you mask any confidential information):

I need a Cost Rollup calculation I can use to compare to every level of a BOM to make sure we are making accurate item quotes.

Version (include the version you are using, if applicable):

24D

Code Snippet (add any code snippets that support your topic, if applicable):