It is not permissible for you to increase the prices
which are fixed by the authorities. It is also not permissible for you to give less in measure and weight even if your father orders you to do so as there can be no obedience to any creature which involves disobedience to the Creator. (Part No. 13; Page No. 96)
May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.