The first numeral after the decimal place is tenths. The second is hundredths, and the third is thousandths. 0.18 is already rounded up to the nearest thousandth; you can't round it up because there is no ten thousandths to round it up from. Sorry; this is a little confusing.
52.0
78.5
2.8
72.0
8.924
It is 6.981 when rounded to the nearest thousandth
34921.000
88.564
70.659
0.370
145 is rounded to the nearest ones. 145 rounded to the nearest thousandth is 145.000
174.689
8.246
287.287
32.346
0.301