Magic Beans, a Boston-area toy retailer and e-retailer, last year began testing a mobile app that let its store customers scan a product bar code, get more product information and pay without ever having to interact with store clerks.

Magic Beans co-founder Sheri Gurock said today that 42% of its smartphone-owning store customers used the mobile self-checkout option over the Thanksgiving holiday weekend last year rather than wait in line to check out at a register. During the entire holiday period 12% of all transactions were completed using the app, from AisleBuyer LLC, an app developer.

The retailer convinced consumers to try the mobile checkout option by offering them an opportunity to get a discount on their purchase.

Gurock said the store focuses on completing transactions faster because its target customers are busy, urban parents who put a priority on speed. A fast checkout option is also good if a cranky toddler accompanies mom or dad, Gurock said. “It’s a convenience,” she said today at the 2011 Shop.org Annual Summit in Boston. “When a parent shops with a toddler, the option to skip waiting in line is very compelling.”

Using the app, consumers can scan a bar code and connect to the product description that appears on Mbeans.com, the retailer’s e-commerce site. They can also read product ratings and reviews. Consumers also can scan the bar code to add the item to their virtual cart and pay with credit card information they store the first time they use the app. In that case, there’s no need for them to wait at a checkout counter.

Gurock said 60% of consumers who scan a bar code with an app go on to purchase the item, and that app users spend more than those who do not use the app, although she did not quantify the increase in spending. She said she expects more consumers to use the app to purchase products in the store this holiday season.

Gurock said the retailer’s next in-store development will be to put iPads in the hands of store clerks and have them roam the store to help consumers complete their purchases. In the ideal future, she said, she’d like to remove traditional register stations and use that square footage to sell more products.