JohnMcDove Jan 22, 2017:

@Jorge y Taña: Estaba pensando lo mismo, pero no encontraba la referencia que tú has encontrado. No tiene sentido que "no se acepten billetes de $20", sino que no se mantienen en la caja. Habría que buscar qué letreros exactos se usan para esto en español. Pero sin duda, Taña, has dado en el clavo en cuanto al significado correcto. :-) (IMO, claro.)

Jorge Merino (asker) Jan 22, 2017:

@ Taña Muchísimas gracias Taña, esto tiene bastante sentido.

Taña Dalglish Jan 22, 2017:

@ Jorge Does it have anything to do with this?
https://blog.safeandvaultstore.com/robbery-deterrence-manual...
ROBBERY DETERRENCE SIGNAGE Robbery deterrence signage, stickers, decals, etc. are available to let customers and potential robbers know what a store is doing to deter robbery. For instance, placing a height measure by an exit door helps witnesses determine the height of a fleeing robber. **Also, to publicize a low cash policy, cards that reads “no 20s” or “no 50s” can be placed in the cash register drawer. These cards also remind the employee that large amounts of cash go directly into the safe.**
But remember, whatever signage you have in place, make sure it is telling a true story. Do not post signage which is not true.
More details on robbery deterrence signage are in the additional resources section of this manual.

Jorge, I would therefore say that it is not that the store does NOT accept $20 bills, but rather that as a security measure that larger bills are immediately put into safe keeping! HTH.