How to recalculate data using a specific value without changing the initial result?

I have some workbooks with some data as shown below (a sample file also attached for testing and better understanding)

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Now what I want to do is I want to manually give a certain value to CGST/SGST and using that and just changing the values of Rate column (by using upto 4 decimal spaces instead of 2) in the worksheet recalculate the values in the table in such a way that the value of NET AMOUNT remains unchanged.

Can this be done using VBA ?

NOTE:

By using upto 4 decimal spaces

I mean when it is converted to 2 decimal places it would have to be same meaning 812.88 can be 812.8751 but not to 812.8860.

I want to manually give a certain value to CGST/SGST

I mean I cannot simply give any value to it, it would have to be in the range + or - 0.05 of whatever the current CGST/SGST value is in the worksheet.