GTA 5 is probably going for a Guinness World Record for "game most frequently discounted" or something like that with all these sales going on all the time. We've always said that it's technically on sale all the time, as there is almost definitely some kind of discount on one of the platforms at some distributor somewhere, at any given time.
The game has managed to retain the same full price that it had upon launch, which is rare when first release happened three years ago. Not even the biggest AAA rivals keep their value for so long, but it seems that the game is compensating for the $60 regular price tag with the constant sales.
While the PS4 version of the game is trying to keep up, it is undoubtedly the PC version that sees the most discounts, simply due to the high number of third party digital distribution sites available for the platform. In fact, GTA 5 has hit its lowest price ever on PC last year, going for less than thirty bucks.