Per WMR your scale has to be right down to 2pounds I think it is here in Dallas. I don't keep up with that but what I would do is what someone noted all ready. Know what your weight is an make sure its the same on there scale. Most yards will have there scale right down to the pound (they not only buy...but sell on the same scales..they would love to get "free" stuff but..not give it out for free either)

At our yard, Our scales go to the 0.1 a pound an we have scales that will even weight in the grams but then again we are more of a e-waste and not a steel yard so we are set up a bit diffident.