Does the pharmacist guarantee the money that was lost from the till due to an unintentional error or oversight while charging the customer for the medicine?

The error resulting from forgetfulness in client accounts necessitates a guarantee, because error and intent are the same regarding the guarantee when it comes to people's money. Forgetfulness and error only remove sin, as indicated by the Sharia texts. Furthermore, there is a shortcoming on the part of the questioner in undertaking work that exceeds his capacity for the concentration and scrutiny required in accounting.