High school grades matter to the military?

[Kita The Cheetah]

Okay, so I'm still deciding which branch to enlist in (i'm a junior in high school and signing this summer), and I'm between Navy and Army. So I was just wondering if high school grades have anything to do with enlistment? I know you need a diploma, but still. Because my army recruiter rarely mentions school, but my navy recruiters always like 'have your homework done?' 'what's your gpa?' 'staying up with all your classes?'
maybe he's just being helpful but I was just wondering if your grades play a part in enlistment in any way???