Why is the total tax for my order less than calculated?

[Brian_Oneal]

Following up on the above ticket:

Hi Zack,

Thanks for the quick response. I think that we are on the same page when it comes to taxes on the actual product. Where I am finding a difference is with the taxes charged for shipping.

Lanyard:
Houston County Tax (3%): $0.12
Georgia State Tax (4%): $0.16
Total Tax: $0.28

Decal:
Houston County Tax (3%): $0.30
Georgia State Tax (4%): $0.40
Total Tax: $0.70

Shipping:

Houston County Tax (3%): $0.18
Georgia State Tax (4%): $0.24

Total Tax: $0.42

Total Tax for Complete Order: ($0.28+$0.70+$0.42)= $1.40

According to my calculations the total tax for the complete order should have been $1.40, but the customer was charged $1.28. The order shows that $.55 was charged for Houston County tax, but I am showing that it should have been $0.60 ($0.12+$0.30+$0.18). For Georgia State the order shows $0.73 charged, but I am showing that it should have been $0.80 ($0.16+$0.40+$0.24).

Please advise. 

Thanks