It's going to depend on what all you have going on in your orders. If you just have order amount + tax, it's fairly simple and like Sandii said, I believe you can just use one or two of the 10 or so amount fields they give you. If you're using promotions/discounts, shipping, gift certs or all of the above, it's a little trickier. I don't think they have amount fields that cover all of those. You might just have to run a search with all Amount fields visible and then back into the subtotal with a formula.