You first look at the third decimal place. In this case it is 7. Then you look at the decimal place after that (the 4th one) and if it larger or equal to 5, then you round up. If it is 4 or smaller, then you leave it be. So in this one 55.06756 = 55.068 to 3 decimal places.
85 rounded to three decimal places is 85.000
13.6599 rounded to 3 decimal places is 13.660.
0.938
It is already 3 decimal places - nothing more needs to be done.
It is 7.103
3.446
6.045
99.229
6.857
As there is no decimal point in your set of numbers it is impossible to round it to three decimal places.
86.3624 rounded to 3 decimal places is 86.362.
We can't round 61.65 into 3 decimal places. But 61.65 is equal to 61.650 in three decimal places.