Is it permissible for me to say, "O Allah, make its reward for me and for my deceased parents," after every good deed I perform, such as acts of charity, glorification (tasbih), seeking forgiveness (istighfar), and reciting the Quran?

It is permissible to dedicate the reward of good deeds to the deceased, and the preponderant opinion is that this reward reaches them. The questioner can dedicate the entire reward of their deed to their parents or include them in it. As for tasbeeh after prayer, it was not reported with the number mentioned in the question. Rather, what was reported from the Prophet (peace be upon him) is tasbeeh thirty-three times, tahmeed thirty-three times, and takbeer thirty-three times, or ten times each, or twenty-five times each along with tahleel.