Modern kitchen models

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Haha, it's okay

Yeah, the top isn't rounded but the sides are rounded-ish. Is there a better way to do this except adding more edges and making them round looking?

Well that's what a normal map is usually used for. (Apart from faking surface details) You make a highpoly model with rounded edges, then bake a normal map from your highpoly to your lowpoly. It makes your lowpoly looks as cool as your highpoly, without it needing more polygons.
Of course, like Rapture said, with your model having so few polygons, beveling the edges wouldn't hurt either. But you could use a normal map anyway to make your model more interesting, so why not bake one! (You can combine a baked normal map with one you made from a 2D texture, too, by overlaying them with certain layer settings in Photoshop.)

Since I've never worked in Blender, I can't really give you a tutorial for that myself, but if you google something like "Blender normal map baking tutorial" you should find something rather quickly. It's a core element of 3D modeling for real-time use so there's a lot of good tutorial material for it out there.