I’m sure it’s a much lower percentage at CVS but cigs are 40% of convenience store gross sales and likely higher profit percentage.
http://www.csdecisions.com/2013/06/21/cigarettes-still-king-2/
That much, wow. But I doubt it would be the same for a pharmacy. Maybe someone else knows.
Tobacco is an absolutely necessary leader item for convenience stores (especially ones with gas pumps).
I can’t speak for now, but years ago when I was a vendor (not tobacco), the store buyers told me that cigs were not particularly profitable, but they had to have them to get traffic.