A close refuses while bills are open, which is correct at end of day and impossible at six in the evening when the shift changes mid-service.
A hand-over is a different verb. The session stays open as the drawer's envelope for the business day; the operator change is recorded as its own event. Open bills deliberately do not block it — that is the entire reason it exists.
The count is authoritative and any variance is attributed permanently to the outgoing operator's segment, then neutralised immediately with a system adjustment. Without that, a shortfall would sit in the session and surface at close-out against whoever happened to be holding the drawer at eleven — the wrong person, hours later, with no way to attribute it.
Approval is inline and synchronous: a manager stands at the terminal. Once the outgoing cashier has walked away the money is in somebody's hands and the count can no longer be re-observed, so a retroactive approval would be meaningless.