Is the phrase "on a scale of 1 to 10" used often if at all?
To rate something, I would say:

(要)在十分內打個分數，(我會給六分)
On a scale of 1 to 10, (I would give it a 6.)

在十分內 = Under a score of 10, 要 is just optional.

Other ways of saying are:


若要评分，我会给...(To give a score, I would give...)
如果要我给分数，我会给...(If I have to rate it, I would give...)


It is not frequent in Chinese to say something like this, comparing to English. That Google translate is definitely wrong.