As has been said numerous times, this is a bullshit excuse. If the register is capable of calculating the taxes, an electronic price tag system ( which is the norm in all big chain stores in Western European countries, which have multiple geographic locations and have locale-specific prices) would too.
If you're referring to the digitally updated signage at the shelves (e-paper or otherwise), none of the stores I go to in NYC have that except Best Buy.
It may be weird for you when you visit, but, as we all grew up with it, it's just normal here.
