As online sales boom, there’s an inevitable side effect: More merchandise is getting returned, boosting costs and complexity for retailers. The shift can be staggering. “Shoppers return 5 to 10 percent of what they purchase in store but 15 to 40 percent of what they buy online,” David Sobie, co-founder and CEO of Happy Returns told CNBC. Not being able to see an item in person accounts for part of the difference, but consumers also shop differently online than in-store, Sobie said. They may order multiple sizes or colors to try on at home, and then ship or take back what they don’t want, with shipping paid for by the retailer, both ways in some cases. Read more at CNBC.