How much to tip at restaurants: At restaurants, tip 15% to 20% of the bill, based on quality of service; if the service is bad, it's customary to tip as low as 10%. For bartenders, tip $1 per drink or 15% to 20% of the total bill
How much to tip for taxis: 10% to 15% of the fare, based on service
How much to tip for hotels: $2 to $3 per night for housekeeping; $1 to $2 per room service delivery, regardless of service charge; $1 to $2 per bag, or more if the bags are very heavy, for porters; $2 to $5 for valet; $1 to $2 for doormen if they hail a taxi; $5 and up per difficult request for a concierge, although it's not expected