LTspice IV How can I get round value with 4 point digit?
Right click on the current label and edit the expression to display to

round(V(n001))

for no decimals, and to 

round(V(n001)*10)/10 

for 1 decimal, etc.

You can use "$" as well, which is an aliases of the current selected voltage node.

To make the value automatically changing and always showing at most X significant digits (1), you can use

round(pow(10,YYY-round(log10($))) * $ )/ pow(10,YYY-round(log10($)))

where YYY is X-1.

e.g. 

round( pow(10,2-round( log10( abs($) ) ) ) * $ ) / pow(10,2-round( log10( abs($) ) ) )

will show the voltage in 2+1 = 3 digits.

For currents, you only can use I(..), so, e.g.

round( pow(10,2-round( log10( abs(I(R1)) ) ) ) * I(R1) ) / pow(10,2-round( log10( abs(I(R1)) ) ) )

The abs(...) makes sure the log10( ) picks the correct magnitude of the value, independent of the sign of the value.   

To make the equation even more perfect, zero values should be covered as well, making the equation even bigger and more complex:

if(abs(I(R1))&gt;0, round( pow(10,2-round( log10( abs(I(R1))+1pA ) ) ) * I(R1) ) / pow(10,2-round( log10( abs(I(R1))+1pA ) ) ), 0)



(1) Sadly, LTspice eats the trailing zeros...