discount. If you charge substantially more than that, then that's unfair and profiting off a national emergency. If they truly charged $15 for a pack of toilet paper that every other week of the year sells for $5 or less, then that's price gouging and taking advantage of the situation. But if you want more detail of what is deemed "fair", you can check Florida's AG page. (Publix is based in Florida)
The law compares the reported price of the commodity or service during the state of emergency to the average price charged over the 30-day period prior to the declared state of emergency. If there is a “gross disparity” between the prior price and the current charge, it is considered price gouging.
I would say raising the price 200% (assuming it normally costs about $5 for a 4-pack of TP), that would qualify as a gross disparity in my book. About the only thing that might save them is whether or not you consider toilet paper a commodity. I would say that TP qualifies as a commodity as they define it which is something you use as a direct result of the emergency. Being stuck and home and needing to wipe you but is definitely something you need more of as a result of this emergency.
https://myfloridalegal.com/pages.nsf/Main/5D2710E379EAD6BC85256F03006AA2C5?OpenDocument