Today's Little Golden book is Colors Are Nice. The date inside is 1962, but because there is a UPC code on the back cover, I am going to guess that this copy was printed after that, seeing as I found this bit of info on UPC codes on Wikipedia.com
"The first item ever scanned in a retail establishment (Marsh's supermarket in Troy, Ohio) was at 8:01 a.m. on June 26, 1974, and was a 10-pack of Wrigley's Juicy Fruit chewing gum. The entire shopping cart also had barcoded items in it, but the gum was merely the first one picked up by the cashier. This item is currently on display on the Smithsonian Museum in Washington, D.C.."