Who can help finding scolarships for American 5th grader to register at the International School in Germany?

I don't know a lot about scholarships but I don't think an American company/foundation would sponsor an American to study overseas and also don't see why a school in Germany would sponsor a foreign student.

Have you looked into this at all? Why exactly do you want to send your son/daughter (I assume) to study in Germany at such a young age?

I have never heard of fifth graders receiving scholarships unless they are exceptional.