Don't make it too difficult for them to open or they may cop an attitude. I once forgot and taped 2 zipper pulls together on an equipment case. They probably struggled a bit to get it open (that's the point), and graciously re-sealed the zippers with about 8 wire zip ties you needed cutters to remove.

I'd assume they're going to hand inspect, and try to plan accordingly. We travel with 4-6 cargo cases, and every one is opened every time.