Should be reasonably easy to work that one out. It so happens that I do consultancy work for a major UK supermarket. So a store tends to be worth about £20 million, has £2.5 million of stock and £100 million per year of sales.
So assume it takes 2 years between the complete loss of the building and them building a new one and getting the business back, it would cost about £223 million per fire. Work out how many they loose per year and can do the trick.
Reputation damage and injuries and deaths however don't have a value that is so easily measureable, but it'll give you a shot in the dark.
That said, it is kinda of irrelevant, as to get the large compartment sizes that supermaket owners tend to want, sprinklers tend to be necessary to comply with Building Regs. Very few supermarkets I visit don't have sprinklers.