$52.32 bought the cheapest comparable cart at Walmart after its new rollbacks, versus $58.52 at Kroger and more than $70 at Amazon in a nine-category price check.
Walmart led on staples tied to the promotion, including sweet corn at $0.25 an ear, cherries at $2.50 a pound and ground beef at $5.94 for 1 pound.
Kroger stayed close by undercutting Walmart in some categories, with ice cream at $1.99 and a temporary Lay's deal at $1.99, though many discounts required a loyalty card and expired within seven days.
Amazon matched Walmart on some items such as $2.50 Lay's chips, but wider price swings and higher soda and plate costs pushed its basket out of contention despite delivery convenience.
The comparison suggests Walmart's summer cuts improved its value lead, but the margin over Kroger was narrower than expected because Kroger's rotating promotions can briefly rival rollback pricing.