Yes! Here's how:
iPhone and iPad
To re-sequence items in your estimate on an iPhone or iPad, tap "Edit" in the lower left corner. This will display a "grab" icon to the right of each item. Press on the "grab" icon and drag the item to anywhere in the list.
Mac
The Mac version allows you to drag and drop items using the mouse. Left-click and hold the mouse button down on a line item, then drag it anywhere.