Best way to handle an extra charge for a shopping cart

If a customer orders less then some minimum amount, an extra charge ($10) needs to be added to the cart.

I was thinking of making a "product" called "Less than Minimum" with a cost of $10 and programatically  add it to the cart when the condition is detected but that feels a little hacky.
I'm also concerned about the "special product" showing up in lists and searches.

What would be the recommend way of implementing such a fee ?

Just weighing in here, I don't have a solution but wanted to mention it is a common ecomm. feature to allow a "minimum order" amount.  Typically it would be entered in Order Settings with such things as "next order number".

Hi Tim,

 Your best bet is to create a custom order calculator.

http://www.sitefinity.com/documentation/documentationarticles/developers-guide/sitefinity-essentials/modules/ecommerce/orders/creating-a-custom-order-calculator

I hope this helps.