Interesting recent bit of info behind JB's price matching from their CEO Terry Smart:

“Our direction to our staff is to take the deal,” Smart said. “We want them to take the deal and let us worry if it’s [profit margin] a bit skinnier than maybe it should be.

“But we would rather bank those dollars than let somebody else bank those dollars.”

Smart said deals offered were “up to the staff” but it was driven by how competitive the market may be.

“If they’re [customers] going into a competitor’s store, getting a price [and] bringing it into us, we tell the staff, ‘Take the deal. Move on, move to the next customer’,” he said.

Source