[Zope] Finagling Around Strange Zope Quirk

Hi; I have a variable that is set thus: <dtml-call "REQUEST.set('shipping',_.int(subtotal)*.05)"> and sent in a form thus: <input type=hidden name=shipping value=<dtml-var shipping>> where I would like it to be called thus: <dtml-var shipping fmt=dollars-and-cents> That doesn't work. I thought maybe it had been converted to a string, so I tried this: <dtml-let shippingit="_.int(shipping)"> <dtml-var shippingit fmt=dollars-and-cents> </dtml-let> but that threw an error that it was already an integer and could not be converted. I give! How do I get this variable to render in dollars-and-cents? Can I convert the integer into a string and work that angle? TIA, BenO