I have a digital scale. When something comes up as 1.00 pounds on my scale, or maybe even 15.98, I round up, figuring my scale may not be quite as accurate as the Post Office's (or at least not calibrated that closely), especially after having already estimated the weight being over a pound and quoting a corresponding charge in my listing. I know my scale is close to what is at the counter, but I don't want any problems after the package is in the hands of the USPS.
As to refunding the customer, no. Maybe in some cases, but not this one. The item was originally listed as "For parts or not working," and completely untested. He talked me into testing it out, which took significant time and effort, and upon telling him the results of my testing, he bought it at the price that I had set based on it being untested and for parts. I probably could have just jacked the price up after my testing, but I didn't. He was very happy with what I did and with what he got, I was happy to move it out, and I'm happy to have now recovered a little extra for all that extra effort.
