Shopify Fees

[Beatsbro44]

So I get the basic plan 2.9% and $.30 per transaction and that it takes off from total amount but why then did the order come to $155.33 and shopify took $8.56. 2.9% plus 30 cents that should come to $150.52 and instead it took it down to me receiving $146.77. I do not understand what is going on can some one explain?