Most cron daemons understand /10 to have a job run every ten minutes. And installing random binaries from the web is rarely a good idea – especially since this very version of grive is already in Debian (unstable/testing):

  $ rmadison grive
   grive | 0.2.0-1 | jessie | source, amd64, armel, armhf, i386, ia64, kfreebsd-amd64, kfreebsd-i386, mips, mipsel, powerpc, s390, s390x, sparc
   grive | 0.2.0-1 | sid    | source, amd64, armel, armhf, hurd-i386, i386, ia64, kfreebsd-amd64, kfreebsd-i386, mips, mipsel, powerpc, s390, s390x, sparc

Edit: And git-annex apparently already has a googledriveannex, giving you all its nice features (e.g. local encryption).