Thank me later

I... I don't know what men's rounded is as it isn't listed. Lol

I guess it's a rounded neckline on a men's T-shirt

@ewqua is correct

I definitely see why one would prefer it. Women's rounded necklines are usually really wide and deep.
Personally my favorites would be off-shoulder (or rather almost off-shoulder? like at a 45° angle, idk if it has a name haha) and high neck.