I changed the code as directed and it now looks like this
$this->Shipping = array();
if(isset($_SESSION["eCartCheckoutForm_shipping_state_province"]) && $_SESSION["eCartCheckoutForm_shipping_state_province"] == "TX") {
$this->ShippingIsTaxed = true;
} else {
$this->ShippingIsTaxed = false;
}
The cart is still not taxing the shipping.
Jan