TAX ROUNDING SETUP Update

I wanted to check with you is on how can I update the TDS ROUNDING SETUP to a back date. The current scenario is that we have gone live effective 26-FEB and we did the TAX ROUNDING SETUP for TAX BASIS starting 27-FEB and now when I am validating the invoice it is asking me to do the setup for TAX. Basis this I have gone ahead and defined the same. But now the problem is that when I validate the invoice it says that the TAX ROUNDING SETUP is not done for the current period i.e. FEB-2014. Could you