You probably don’t need a different lens. The main issue is technique: when you angle the camera or the DVD case, a flat subject no longer sits in the same focus plane, so parts of the text fall outside the very limited depth of field you get in close-up shots.

For best results:

• Keep the camera square/parallel to the DVD case.
• Don’t use the built-in flash straight at the cover.
• Light the case from the sides or above with diffuse light.
• A light tent/light box, white sheet diffuser, or open shade outdoors can help control reflections.
• Since the case won’t move, use slower shutter speeds if needed instead of harsh flash.

A plain background and soft, even lighting will usually give better listing photos.

If you already own a flatbed scanner, it may produce even better images of DVD covers than a camera for this specific job.