5 CFR § 591.213 - What prices does OPM collect?
(a) OPM surveys the price charged to the consumer at the time of the survey. The price includes any sales, excise, or general business tax passed on to the consumer at the time of sale and any discounts, mark-downs, or “sales” in progress at the time the price was collected.
(b) Exceptions: (1) OPM does not collect coupon prices, clearance prices, going-out-of-business prices, or area-wide distress sale prices.
(2) OPM prices automobiles at dealers and obtains the sticker (i.e., non-negotiated) price for the model and specified options. The prices are the manufacturer's suggested retail price (including options), destination charges, additional shipping charges, appropriate dealer-added items or options, dealer mark-up, and taxes.
(3) OPM estimates prices for selected items, such as health insurance and K-12 education, based on employee usage of the item. For example, OPM estimates health insurance prices based on the employee's share of the premium costs and weights reflecting Federal enrollment, as reported in OPM's Central Personnel Data File, in the various plans available to Federal employees in each area.