You have made an estimate in the form of an Excel table:
- you have added each sub-totals and get a total HT (in E8 for example), followed by a discount (in E9), the VAT applied (E10), got your Total Price VAT included .(E11)
- your client asks you to round the tax amount ..... (in E11)
- You do not want to change your Total HT (E8).
- You may not edit your VAT applied (E10).
- You can change your Discount (E9).
Go to: Tools > Goal seek > Select cell .. Clicking E11 (your Total TTC)/Value to reach ... you specify the value you want to be displayed ... Click on E9 (Discount) .... OK.
- Excel recalculates the discount (E9) to reach precisely exact final value (E11), and also adjusts your VAT amount (E10) without changing the rate.