The instructions don't mention the accuracy, although they do state the READABILITY is +/- 0.01. The other reason I chose this one, is exactly your point Grainger. Max weight is only 5g, more than enough.
I also agree with you that many think that since it displays to 0.01, it's accurate to 0.01, which is incorrect. Same applies to any digital measurement display (multimeters). (Analog rules in vinyl and readouts!)
Anyway, I purchased a 5g calibration weight at the same time. I could question its precision too since it was also dirt cheap, but at some point you need to take a leap of faith. Since it measured very close to what I was expecting, I'll believe it. It is also consistent. I measured several time over a few hours, it's always 1.56g