Levantar la mano
 

Levantar la mano in Spanish is an idiom that means, to pass somebody in an exam, because they are close to get a 5. How can we say it in English?

To be honest, I'm not familiar with that usage. Can you use it in an example sentence?

I think you can use, let somebody get by with a C.

The literal meaning of the Spanish phrase is "Raise your hand" in English.
Am I right?

@idioms, yes that's the literal meaning.

@ROBINDESBOIS, I think you can just use "to pass (the student)". For example, "Jim did horrible on the exam, but the teacher decided to pass him anyway, after seeing how hard he tried."

Note: When talking about a "5", that is on a 1-10 scale where 10=100%.

ejemplo:

No os preocupeis , si al final os quedais cerca del aprobado, levantaré la mano.

I'll let it go. (I'll let you pass.)
I'll let it by.
I'll waive you through.

All mean that it's close enough (worth the effort given) to allow a rounded-up grade.

Spelling intended, or should that be wave you through?

Spelling intended, with the meaning of 'refraining from insisting on' an exact midpoint. If the student is close to a 5, the teacher will dismiss considering that better effort is necessary.