You are on the right track to become a Super Shipper! I love when sellers do their research prior to shipping. Be sure to read through some posts regarding getting paid after so you also know what to expect. After the first few shipping transactions you will get paid lightening fast!
My post office can't do it so I canceled my order and reposted with correct shipping weight. My first order was a typewriter (yikes!) I was off by 1 lb however I asked the post office to weigh it for me to be sure since it is heavy, oversized and going to Texas. They said $60 is the total cost for shipping. There is no way I would want that mistake to happen even on 1lb over since Offer Up has a discounted rate compared to just standard USPS rate. Thats why USPS cant do what Offer Up rates will cost. Better off weighing first so customer doesn't get stuck with overage cost. Needless to say I reposted and offered a break on the price.