In Point of Sale, tap "Other Tasks", and select "Reprint Tickets".

If you know the transaction number, you can search for it here, otherwise use "Advanced Search" to find the transaction by other means.

Once you have located the transaction, simply tap the "Reprint Tickets" button underneath the transaction view.

NOTE: Reprinting tickets is not enabled by default, and must be enabled in Back Office by a user with Director-level access.