Thanks for the screenshot, we see you have an extra column in your order system (pardon the spelling) “Κ?ατο? Aγορα?” which we are not sure what pricing that is. Our “Cost (Incl)” pricing column is built to work the same as the “Κ?ατο?” column so showing the cost per item but inclusive of tax and when you edit the costing for one, WooCommerce automatically calculates the taxes and totals. You can see this better in this screenshot: https://ibb.co/zPYCS6R
So the Cost (Incl) and Cost columns are both for 1 item x the Qty to then show Total (Excl) and Total Tax. The Total of the order is still available. We can look at adding a Total Cost Incl field per line item as well but for now I believe the plugin is working as intended.
I hope the above moakes sense, please let me know if anything is unclear or if you feel I am missing something and thank you again for the feedback and screenshot!