Oh, you still need the voltage divider. 10V would otherwise damage the analog pin. But, think about it: an output of, for example, 7.4V from the sensor would get reduced to 3.7V by the voltage divider. This would give a reading of around 757 or 758 from analogRead(). You could then calculate the input voltage as 757 / 1024 * 5. But you would still need to translate that back to the 0-10V range by multiplying the result by 10 / 5. So the formula would be 757 / 1024 * 5 * 10 / 5 and, voilá, the 5s cancel each other out.
PS. I updated my previous reply before I realised you had responded. Please re-read.