Bags should be locked with TSA approved locks, which can be opened by TSA personnel, using a universal key. The approved locks can be purchased locally and come in a variety of colors. Non-approved TSA locks will be cut open in the event the bag needs to be opened. 

It is not recommended to tape boxes shut prior to check-in and TSA screening, as they may have to be cut open for contents' inspection.

TSA Approved Lock