Hi,
Base currency for CRM 2011 can be set when a new organisation is created. There is unsupported fix to change this behaviour though. Find the article below for the same.
http://kirsanov.net/post/2011/11/18/Changing-base-currency-in-Microsoft-Dynamics-CRM-2011.aspx
If you are looking at adding new currency for Indian Rupees, create new system currency from Settings -> Administration -> Currencies -> New Currency. This will allow you to create indian currency with the exchange rate.
Hope this helps.
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Minal Dahiya
blog : http://minaldahiya.blogspot.com.au/
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