[ic] [Q] How to use the user tag in calc

[Xiaowen Wu]

Hi, I'm new to interchange, and I have a very simple question, I would
like to calculate the shipping fee based on the sub-total, in other word,
the shiping fee = subtotal * 0.035, so I put the following into the 
checkout page:
	
  [calc][subtotal]*0.035[/calc]

but I cannot can the correct value. What I'm missing ? Thanks in advanced.

Best,

Wen