Wanted to boost this back up again with some more information:
I went in today and grabbed a scale from Office Depot, which will tolerate up to two pounds and just got done testing it out. I'm not sure if the postal scale was off or what but I weighed an example package, the kind that I've been sending off recently, and it barely came out 2 ounces, 3 under the quote I got from the post office. Knowing this now, I'll be able to input the right weight when I'm printing shipping labels which should hopefully help me save on money and adjust shipping costs in the future.
Very glad I made the purchase and would suggest it to anyone.