Arranging Invoice Items by Category

Hi,

I am in the process of transitioning from Opencart (my current ecommerce platform) to WordPress & MarketPress. My website is an online grocery store, containing at the moment about 1,300 products for people to buy and then we deliver those products to their home.

We physically go to the grocery store for our customers, and do the shopping for them, bringing along their order invoice as a shopping list.

I am wondering if it would be difficult to make it so that when I get an order notification (whether email or in the WP backend, or both), the products are listed by category. The categories don't need to be in any specific order, just each product under it's proper category heading.

I am familiar with WordPress development and PHP, so a point in the right direction or a code snippet would be great

Thanks!