Massachusetts explanation of the retail pricing requirements.
http://www.mass.gov/ago/consumer-res...uirements.html
Abbreviated version, leaving out exceptions like rope and live animals etc.
The Attorney General’s Item Price Regulation, 940 C.M.R. 3.13, applies to non-grocery stores or to the non-grocery items of a mixed-product retailer. The regulation requires, among other things, that such merchants mark goods offered for sale with the selling price by either affixing a price tag or sticker on the product or its packaging, and states that it is an unfair or deceptive act or practice in violation of the Massachusetts Consumer Protection Statute, G.L. c. 93A, to fail to do so.
Sellers are obligated to sell goods at the correct price,
which is the lowest of the advertised price, the posted price, the sticker price, or the checkout price, and must clearly and conspicuously disclose to a buyer the exact nature and extent of the seller’s refund, return or cancellation policy prior to completion of the purchase transaction.