Quickbooks Online refund detail

1. Quickbooks Online Simple start is 50% off for 3 months
$15 * 3month + $30 * 9month = $315
Why total amount $320?
2. Quickbooks Online Free trial for 30 days and 50% off for 3 months.
I have a free trial for 30 days, why I pay for term fee?
3. I was refunded like the picture above. My term fee is $12.58.
So, Total paid $320 - $12.58 = $307.42
Why you refunded me only $291.18?
Please, explain it to me. And what % is the tax?
