Hi Samantha,
Yes. There is a way to show the item cost per variant in NAV/BC.
But first, you need to setup the system to be able to compute the cost into item variant level with the "Average Cost Calc. Type" field "Inventory Setup" table.

Once setup is done. item ledger Entries can show the average item cost per variant level for the transactions that are posted after the setup was done.

I hope this helps answer your question.
Aicen