52 is rounded to the nearest thousandths. However if you need to indicate that it is, you should write it as 52.000
45.0099 rounded the nearest thousandths is 45.010
It is already rounded to the nearest hundred thousandths. Rounded to the nearest thousands would be 87.381.
42.746
37.210
329.546
0.968
100.000
3.299
51.550
342.964
409.020
0.200