Most guys won't worry about the 2%, but if you adjust your pricing at the estimate stage by figuring out how much you want to charge the client, then divide that amount by .98 (100%-2%) you will have an adjusted retail price that allows you to offer the discount without cutting into your needed profits.
If you wanted to make this more substantial, you could do this with a 5% or 10% discount and still maintain the level of pricing you need for overhead and profit.
