Cart software that works well offline?

My client wants a cart-driven site but does not want to do any payment processing, including PayPal. He wants to manage his inventory with the cart so he wants customers to fill their cart, check out without collecting a payment, he gets notified of the pending sale, and then he will bill them through an invoice. He wants inventory to be adjusted at the time the customer checks out and he will add items back to inventory if payment isn't made (although handling that automagically through the cart would be awesome). Lastly, he deals in multiple currencies and exchange rates are all over the place. In terms of the cart that means he does not want currency conversion but would like the ability to post prices in varying currencies - all in the same cart (calculations do not have to be performed within the cart, he'll do that in the bill he sends the customer).

I know that there isn't a cart that will handle all of this goals and I've used several that have at least some of the functionality. My question (finally!) is which of the carts offered by InMotion comes closest to meeting his criteria? Thanks!