Display count resolution for any digital readout instrument is always plus or minus 1 least significant digit. (This is because you obviously can't display a fraction of a digit in this position - not to be confused with "half-digit" displays where the most significant digit is either blank or 1, e.g. 3 and half digit display can show a maximum of 1.999, 19.99, etc.)
The accuracy is primarily determined by the measurement system which drives the digital display (e.g. how many bits in the A to D converter)