Late last year, Dollar General CEO Todd Vasos told a Goldman Sachs retailing conference that his stores’ average shopper is, typically, a woman living a two-income household, making $40,000 per year before taxes, and clinging to a stable job with no wage growth. He says that shopper’s disposable income is around 2 percent, so $800 per year, and her shopping habits don’t respond well to price changes of as little as a dime.