The interviewer wants to know how much training you will require, should they hire you and also - if you are a trustworthy person who can handle the responsibility of cash handling. Share where you cashiered, how many years you were with that company, and share how accurate your drawer usually was. You can also include info on how much money you handled on a usual day.
"In my current role I handle approximately $5,000 in cash per day. I have never had a discrepancy in my cash-out and am fully trustworthy."