I see TV's at Walmart, Target and Sam's Club, but come to think of it, never bought a TV at a mass merchant. OTOH I've bought six TV's and three receivers from Best Buy. Sales tax isn't really a factor. I just want to see what I'm buying. If the price is acceptable it doesn't matter if it might be slightly less across the street or online. Also the salesmen don't matter. I usually know what I want and may only have a question or two. So Best Buy gets most of my business.
I do buy some gear online from Amazon and NewEgg. As for those who browse products in stores then order online, I actually did just the opposite. I saw an Onkyo receiver at a good price on Amazon and went to look at it at BB... didn't like the Onkyo, but they had a Denon right next to it that I liked and bought it on the spot. I'd hate to see the day when we have to buy everything sight unseen online because all the B&M's have stopped selling electronics.
Polk RtiA9's, Denon 3312ci & Emo XPA-5 amp, CsiA6, RtiA7 surrounds, FxiA6 rears, twin Klipsch Synergy Sub-12's, DSW660 & Lsi9's upstairs