American living in Japan here! As for tipping in the U.S., check the receipt. American receipts have a section for tipping. It will be labeled either "Tip" or "Gratuity." As they said at Philippe's, tips are worth 15-20% of the total cost. I usually calculate this by doubling the tax charged, which in California, is 9.5%. If your receipt has no section for tipping, you don't need to tip. If it does have a section for tipping, then tip. Also, those "cancer warnings" you saw at Nijiya Market in Los Angeles, that's due to a 1986 law called Proposition 65. The voters of California approved a law which requires warning labels for things which contain chemicals believed to cause cancer. Problem is, everybody issues these warnings so as to avoid lawsuits. We Californians ignore these warnings. すみません、私の日本語がごがゴミです。