Custom Tax on custom shipping

I have multiple tax rate for multiple jurisdictions.
I also have some items that are subject to tax and some that are not.

I have successfully setup all of the shipping rules to cover particular products and jurisdictions. That works fine.

I have one tax that applies to all products sold to customers in Canada. Works fine.
The other tax, only applies to some products in some provinces. I have all of that coding done and it works perfectly.

My only issue is with tax on shipping. I cannot use the simple check box for tax on shipping because one tax is calculated as a factor of the products sold so what I need in one of my tax rules is essentially this:

$totalTax += ((($this->TotalColumn("PSTCalc")+($totalShipping)) * ($_SESSION["taxprov"])));//Result

Where $totalShipping is:

<?php echo $eCart1->GetShipping(); ?>

As is often the case, I am sure my problem is simply syntax because the rule as I have it does not throw any errors, it just does not include the shipping value in the tax calculation.

Can anyone help?