Retrieve deducted value POS system

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VB

Good day asking for help.

I'm trying to make a POS System using VB.Net 2022.
My problem is on how to retrieve the value deducted qty when the transaction is canceled .

What I have tried:

Ex.
tbl_item
---------------------------------------------
Barcode | item_name | item_qty | item_price
1234555 | Chips     | 95       | 20
1284588 | Bread     | 95       | 20

tbl_invoice
----------------------------------------------
invoice_id | item_name | item_qty | total_price 
1000000    | Chips     | 5        | 100
1000000    | Bread     | 5        | 100

Scenario:
When the item is scanned 
the qty should deduct based on amount of qty.
then save in tbl_invoice
and put in DataGridView.

When the transaction is canceled the qty should return to the specific item in tbl_item.

Private Sub btn_cancel_Click(sender As Object, e As EventArgs) Handles btn_cancel.Click

What so I do?
Thank you.

End Sub