To Set Decimal Places of Dimensions
For Dimensions with Rounded Value
Set the value of the default_dec_places configuration option for linear dimension and default_ang_dec_places for angular dimensions to required number of decimal places. Any dimension that you create will appear with the defined decimal places.
For existing dimensions, select the dimension or select multiple dimensions using CTRL key. The Dimension ribbon tab opens. In the Precision group, select the Round Dimension option and specify number of decimal places.
Alternatively, for a Drawing dimension, select the dimension, and on the Annotate tab, in the Format group, click 
Decimal Places. You are prompted to select the number of decimal places. Any dimensions selected or created after this are displayed with the designated number of decimal places.
Decimal Places. You are prompted to select the number of decimal places. Any dimensions selected or created after this are displayed with the designated number of decimal places.For Dimensions with Non-rounded Value
The initial decimal places value of the dimension is the number equal to the number of significant digits after decimal point of actual dimension value.
Select the dimension or multiple dimensions. The Dimension ribbon tab opens. In the Precision group, de-select the Round Dimension option and specify number of decimal places.
If you select a driving dimension and modify the decimal places value, the actual dimension value is modified in case the defined number of decimal places is less than the number of digits after the decimal point of the current actual dimension value.
However, if you select a driven or programmatically driven dimension, you cannot specify decimal places value that is less than the number of significant digits after decimal point of the actual dimension value.