Shirts and collars would be similar to the Inverted Triangle. If neck is short or thick though, keep away from Oxford cloth and button-down collar. Shoulders are more narrow. Dont wear a suit that is too snug in fit. Try for a Modified European cut suit which will artificially extend the shoulders to balance the hips and project more strength.
Peaked lapels create a broadening illusion of the shoulders.
Ties need some width, but still need to be fashionable. Narrow ties will emphasise the narrow upper body, so avoid them. Men with thick or short necks need to avoid high-styled collars. Some men who are athletic, with broad chest, rounded back and often rounded shoulders will create this round shape. Many portly overweight men also fit this shape.