Retail same-store sales edged higher with a 5.7% gain in September as retailers reported a solid tail-end of the back-to-school shopping season despite slightly tighter spending plans by shoppers, according to Kantar Retail. The sales-weighted composite for the 25 retailers reporting most of them apparel retailers is 5.7%, higher than the 5.1% same-store sales gain last month and the 2.8% gain in September of 2010. Note that the calculations no longer include Walmart, which stopped reporting...