undefined method `*' for nil:NilClass

[antarr]

I'm getting this exception using the show.html.erb in the demo application. You can view my current application in my bootstrapped_devise repo.
Thanks,

Antarr

undefined method `*' for nil:NilClass
Extracted source (around line #5):

2:
3: <%= render :partial => 'shopping_cart_item', :collection => @shopping_cart.shopping_cart_items %>
4:
5:

SubTotal:<%= number_to_currency @shopping_cart.subtotal %>

6:

Taxes:<%= number_to_currency @shopping_cart.taxes %>

7:

Total:<%= number_to_currency @shopping_cart.total %>