Drupal commerce user based percentage discount I need to have different order total discount rates in % for each customers. The default discount is 10% for all users and it need to be override for certain users too. i.e administrator can set the different discounts such as 12% for user1 and 15% discount for user2 etc on a specific interval (between valid from and to dates). Is it possible using rules or custom module?

Please help.
Yes, Rajeesh, anything is possible with Rules. : P

In this case, I'd recommend something like a discount percentage field on user profiles that defaults to 10% and is only visible to administrators who can then override the field value on a user-by-user basis. Your product pricing rule can then look for this field to have a value on the order's user (i.e. use commerce-line-item:commerce-order:owner as the token, not the site:current-user) and then apply it as a discount using the appropriate line item action.