[ic] express checkout sales tax display and calculation

[havoc]

How do I get the express checkout page ( pages/ord/checkout.html ) to refresh 
in order to refresh the displayed sales tax in the shopping cart portion when 
the state is changed and prior to final order placement?

The tax is correctly calculated in the receipt after the order is placed.  But 
I need the customer to see it before they place the order and if/when the 
State/Province is changed.

I'm using interchange 5.4.1 installed from the tarball.
My catalog is based on the Standard demo so I think the relevant code for the 
State/Province <select> is in include/checkout/shipping_address:

     <tr>
      <td class="contentbar1" align=right>
         [error name=state std_label="[L]State/Province[/L]" required=1]
      </td>
      <td align="left" class="contentbar1" colspan=3>
        [display name=state type=state_select value="[value state]"]
      </td>
     </tr>


Any help/pointers in the right direction would be greatly appreciated.
Please let me know if more information is required.
Thank you.

-- 

   - havoc