“Usted tendría que devolver los

artículos en la caja. (You would have

to return the articles at the till.)

HINT: Conjugate "tener que"' in El

Condicional Simple.

“No entiendo “the till.” In the US would be the cashier, I think. In Latin America, perhaps “el cajero.” “The till” has various contations in the US and some border on the negative. From Miriam-Webster: 

till

 noun (1)

\ ˈtil   \

Definition of till (Entry 4 of 5)

1a: a money drawer in a store or bankalso  : CASH REGISTERb: a box, drawer, or tray in a receptacle (such as a cabinet or chest) used especially for valuables2a: the money contained in a tillb: a supply of especially ready money