You should always consider giving a tip. The pick-up or delivery fees may go partially toward the earnings of the shopper, but mostly it is a fee the store charges. Remember, your Shipt shopper probably depends on their tips to make a decent living, just like any other provider in the service industry. It is not only polite, but expected that you provide a tip based on the service you received. A tip of 15% is considered customary, with higher percentages appropriate for especially good service or extra effort.