This is the desired look of most bodybuilders when training shoulders. I believe to achieve a rounder-capped look, extra emphasis must be put on training the posterior head of the deltoid. My recommendation would be to start with a compound pressing movement and finish with an isolation exercise such as rear delt flys to make sure all heads of the deltoid are worked in your workout. Remember, isolation exercises carry very little fatigue over to your next session so you can perform rear delt flys at a high frequency to maximize your progress.