If its happening consistently, isn't it edging onto some kind of pricing fraud. Well, fraud seems too strong a word, but IANAL so I can't quite come up with a better one.
Didn't a telecom get in trouble years ago for adding like 2 or 3 cents on everyone's bill? Because of the small amount no single payer complained, but because of volume it amounted to 10s of millions. And it became an FTC case.