It's self-explanatory. Press space to round. I made this because my Sand Physics Engine had a longish script that could only round to 10. NaN means you used a symbol other than a number.
Free to use, no credit needed. A very simple script I came up with that, unlike all the massive scripts that simply round to the nearest 10, can round any number to the nearest any number, even with decimals! This uses the Swedish rounding method.