Currently, there is no such option is cursor settings of Simulink Data Inspector where you could set the decimal precision of a cursor values.
However, the cursor value precision displayed always depends on the time points precision in the plot.
For example, in the image shared by you the time range is between 0-110 seconds. Hence the decimal precision in cursor is 1 i.e data value is 450.0
In case if the time range is between 22.5 – 23.0 seconds, decimal precision in cursor will be 2 i.e. data value could be 223.45
Concerned development team is aware of this and having a UI setting to set the precision for cursor is considered for future releases