Tom Thumbs financial numbers look pretty good in a very competitive market. This is a case where I think that common wisdom may be wrong. Instead, I think you should reward your loyal customers and charge MORE to new customers, who after all, were your competitors customers. This may be somewhat counterintuitive, but I've found it works. It's far easier, and more cost effective for me to retain good customers than to pay to attract new ones.
Most people miss that.
In fact, a lot of businesses can't even tell you how much they spend to get a new customer. Second only to how much the lifetime value of a customer is worth. After all, they've already made their choice of where to live. We both want to keep the lines of communication open and respectfully explore all possibilities for mutual advantage. Personally, I hate coupons.