Encourage people to buy more and to come back to you. Try offering free shipping on purchases over X amount of dollars, free $5 iTunes gift cards with a purchase of $100 or more in electronics. Sure these incentives dig into your profit but they attract and keep a loyal customer base. Of course loyal customers tell their friends about what a great deal or sale you offer and we all know the best type of advertising is word of mouth. Customers love a good deal. No one wants to feel like they are being ripped off. Make your customers your #1 priority. Prove this to them and they will keep coming back.