What are the advantages of pretax pricing?

For example, would you rather see a sign posted for $7.00 or $6.46 plus tax. Obviously it is the same price(depending on your tax rate) but I am doing a marketing product hopefully showing that customers like seeing the cheaper price advertised vs the post tax price. I am not sure what the retailers point of view is because I am not a retailer. All comments are welcome. If you need a point of reference on the product, let's just say a pack of Marlboro--$6.46 plus tax or $7.00. Before you start talking about smoking and the cons that go with that, I am not looking for that.