Compute mehtod of datagridview Count rows

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VB8

VB

My datagrid view is like this

Barcode    Item Name    Count    TAX%   TotalPrice  Profit

1123        Milka        2        18      100         20

21231       Snikers      1        5       50          10

1231        Bountyy      3        18      150         40

13122       Lion         2         5      100         30

Now i want to calculate the tax because there are two type of taxes 5% and 18%
The tax is calculated from the profit.
Example
In Textbox1.text =(i want to show total Tax for articles with 5%)
in Textbox2.text =(i want to show total tax for articles with 18%)

[edit]SHOUTING removed, code block added - OriginalGriff[/edit]