When we used to use inches here my school ruler was marked in tenths on one side. But I think many people who use tenths are measuring in centimetres and converting. In much of the world a metric scale is all you'd be likely to find easily, so you use that, and divide by 2.54 to make the answer traditional, and intelligible to Americans. It's then a lot simpler to round to one decimal place than to round to the nearest 1/4", and it's easier to type, say, 7.2" than 7 1/4" or 7.25" or 7¼".