You can sort the items in your filters by any of the properties you uploaded, price, item code, and more.
Go to Items -> Manage Catalog.
Click on the Filter you wish to sort the items in and click on the Edit Filter icon:
Go to the "Sort By" section of the filter:
Select a property to Sort your items by.
You can also indicate ascending or descending order, by selecting the up or down arrow.
Click Advanced to sort manually, by any order that you decide upon, by dragging the items to the position you want them to be in.