In a recent Wall Street Journal article, which took a look inside Apple's $12 billion+ retail empire, it was revealed that Apple employees are trained not to sell. Instead, they're told to "probe politely and listen for and resolve any issues or concerns." They're even expressly instructed to "Listen and limit your responses to simple reassurances that you are doing so. 'Uh-huh' 'I understand,' etc."
Today's consumer enters your retail establishment interested, informed, and skittish. Your job is no longer to sell stuff and close deals by watching intently for subtle shifts in their behavior. Rather it's to reassure them, and to open up new worlds and new possibilities with your innovative products, services, and ideas.
Goethe wrote, "Few persons are capable of being convinced; the majority allow themselves to be persuaded." Human nature has not changed. Stop trying to persuade people and, instead, help them persuade themselves.