Floyd's attorneys, who didn't contest that Floyd was responsible for the killings, pushed for a life sentence, while prosecutors wanted the death penalty.
The same jury found Floyd, 24, guilty of four counts of first-degree murder last week.
He also was convicted of the attempted murder of a fifth supermarket employee and of raping and kidnapping a former outcall entertainer just before the June 3, 1999 shootings.
Jurors took less than two full days of deliberations to decide Floyd's fate.
Defense attorneys tried to portray the former Marine as an emotionally and mentally troubled man who turned to drugs and alcohol. A psychiatrist who treated Floyd when he was about 13 testified that Floyd had a variety of problems, including attention deficit disorder.
They claim Floyd became mentally unhinged the morning of the shootings. But a neuropsychologist testified during the penalty phase of the trial that Floyd knew what he was doing during the five-minute shooting spree.
Clark County District Attorney Stewart Bell described Floyd as a "hollow soul" who was living out his fantasies when he raped the outcall entertainer and then shot the Albertson's workers.
The defense put a string of witnesses on the stand Tuesday in an effort to save Floyd's life. Floyd and his parents took the stand to deliver sometimes emotional testimony.
A composed Floyd apologized but said he still doesn't have any answers.
"There's not a whole lot I can say to the families of the four people I killed," Floyd said. "I can't take back what I did, but I would if I could."
Formal sentencing was scheduled for Aug. 31, when District Judge Jeffrey Sobel also will decide Floyd's sentence on the attempted murder, rape and kidnapping charges.
Floyd's death sentence recommendation was the second handed down in two days in a Las Vegas court. A jury recommended Thursday that Fernando Hernandez, 38, receive the death penalty for stabbing and strangling his ex-wife. The couple's 3-year-old daughter witnessed the murder.
By Angie Wagner