Problem with sales tax calculated on shipping

So I live in TN, where they require sales tax to be paid on shipping options. I was trying to test a flat rate shipping option on my new Open Cart system, and I am getting an odd problem.

If I add multiple items to my Open Cart cart, everything is transferred to paypal correctly.
(Open Cart info)
//two items in cart (two different items, multiple quantities of the same item doesn't work)...
Sub-Total: $13.00
Flat Shipping Rate: $18.25
TN State Tax 9.25%: $2.89
Total: $34.14

//what paypal displays after clicking Confirm Order
Item total: $13.00
Sales tax: $1.20
Shipping and handling: $19.94
Total With Shipping: $34.14 USD
//It is combining the sales tax on the shipping charges into the shipping charges, which is fine for me.
-----------------------------------------------

But if I only have one item in my cart, this happens.
// one item in cart for $5
Sub-Total: $5.00
Flat Shipping Rate: $18.25
TN State Tax 9.25%: $2.15
Total: $25.40

//paypal says...
Item total: $5.00
Sales tax: $0.46
Shipping and handling: $18.25
Total With Shipping: $23.71 USD
// For some reason if there is only one item in my opencart shopping cart, it never calculates sales tax on shipping.

Odd error. Help?

we have just up graded to 1.48, plus the new paypal module. we will see if that fixes things.

Still having the same problem. It charges sales tax correctly as long as there are 2 different items in the cart. But if there is only a single item in the cart, when it sends the information to paypal, it doesn't seem to be sending the extra sales tax for the shipping costs.

So OpenCart and paypal are listing two different amounts for the total charge.