I grabbed a handful of 1/8" rod and headed off to the UPS scales. I dropped rods onto the scale until I estimated what appeared to look like 5lbs worth and then counted them out. According to our scale(I have no idea how accurate that thing is)...5 lbs worth equals 67 rods.
67 rods x 10 = 670 rods
I would consider this a very loose estimate due to my scale and how wide the needle is against the scale, making it difficult to see exactly where the 5lb mark is (one rod too little vs one too many).
After talking with the lincoln rep, he says that the manufacturing process is very systematic and automated so he said that he was willing to bet that every can had the exact same amount of rods in it.(whatever that number may be) Each rod has the same amount of flux, and the coating thickness is very consistant to keep the amperages fairly close between one rod and the next. Physically only just so many rods will fit into a can, and they do not want the rods to slap around in the can and knock off the flux if they are too loose. So, he feels fairly confident that each can has the same number of rods as the next.