Archana, I think the attached workbook is what you're looking for. I changed your formula from AVG() to SUM() and it produces the numbers the same as your spreadsheet:
Then use the sub-totals to show the category % discounts:
By the way, I'm pretty sure what you wrote here:
Eg: For SKU 1, Discount Rate= 25.43%, whereas we need it to be 1.92% (Refer to Excel Sheet for
...is a typo. It is 4.09% not 1.92%, right?
Also, if you take the Regions off the row shelf you'll get the correct totals for each SKU:
Hope this helps,