Final answer:
The individual responsible for the petty cash fund is called the petty cash custodian, who manages and reconciles the fund according to company policies.
Step-by-step explanation:
The title of the individual assigned responsibility of the petty cash fund is the petty cash custodian. This person is tasked with managing the petty cash fund, which typically involves maintaining the cash box or drawer, disbursing funds for small business expenses, and reconciling the account. Accurate record-keeping is crucial to ensure that all transactions are documented and the balance of the fund is maintained, which is essential for financial control within an organization. The petty cash custodian often needs to follow a company's financial policies and procedures to ensure proper management of the fund.