Shop wide discount function

/ Does anyone know of a app / function / widget / that will switch on and of a shop wide discount, as I want to do a 10/15/20% discount at different times like bank holiday and ive got 1200 products so ts not easy to changr em all

and coupons well I don’t know yet who mighty buy and wen, most of my customers ive never dealt with em yet

If there is nothing, what about one of the design people could they make something?

Simon
‹(•¿•)›
“м α ∂ є ι и у σ я к s н ι я є™”