DAC output voltage is not symmetric around 0 V.
For being sure, that input offset voltage compensation is not smaller than +/-5 V, simple resistor in series with internal DAC resistor for opamp feedback was applied. That should have increased the output range from +/-5 V to ~ +/- 5.5 V. But the resistance of the internal equivalent resistor's resistance vary due to the output DAC value changes, so the output voltage could be changed on the range of -5.5 V to +5 V (where the zero value gave ~ -0.2V). External resistor has been removed to bring the symmetry back.