What is the ruling on taking money from the shop's till without its owner's knowledge, given that the owner has entrusted me with it?

Trustworthiness is one of the fundamental qualities of a Muslim. Allah has forbidden its betrayal, and a Muslim is entrusted with what is under his hand. So, if he takes something from it unlawfully or neglects its preservation, he has betrayed the trust and is obligated to guarantee it. He must return what he took to clear his conscience. It is sufficient for him to return what he took, resolve to repent, and frequently seek forgiveness.