The actual value may be different from what is actually being displayed by MATLAB. For instance, consider the following example:
>> x = 1.4 - [0.1; 0.09999999]
x =
1.3000
1.3000
MATLAB shows both values to be 1.3, but in fact, none of them is:
>> x - 1.3
ans =
-2.2204e-16
1.0000e-08
My suggestion is therefore to decide on a fixed accuracy (say, 6 digits), and then multiply by the corresponding power of 10.