Better yet, 3 items at 0.1 shipping weight at a price of $0.12 each comes to $7.07?

I'm finding no rhyme or reason. I've also read about tare in the FAQ and it almost made sense from my first example, but what makes it think I was shipping a large package? And what is up with $7.07?

Help please... I'm sure it will all make sense soon I hope.