USA Guide
Money
The US dollar comes in $1, $5, $10, $20, $50 and $100 denominations. One dollar comprises one hundred cents, made up of combinations of one-cent pennies, five-cent nickels, ten-cent dimes, and 25-cent quarters. You can check current exchange rates at 
www.xe.com/ucc .
Bank hours are generally from 9am to 5pm Monday to Thursday, and until 6pm on Friday; the big bank names are Wells Fargo, US Bank, and Bank of America. With an ATM card, you'll be able to withdraw cash just about anywhere, though you'll be charged $1.50–4 per transaction for using a different bank's network. Foreign cash-dispensing cards linked to international networks, such as Plus or Cirrus, are also widely accepted – ask your home bank or credit card company which branches you can use.
Credit and debit cards are the most widely accepted form of payment at major hotels, restaurants, and retailers, even though some smaller merchants still do not accept them. You'll be asked to show some plastic when renting a car, bike, or other such item, or to start a "tab" at hotels for incidental charges; in any case, you can always pay the bill in cash when you return the item or check out of your room.
US traveller's checks are the safest way for overseas visitors to carry money, and the better-known checks, such as those issued by American Express and Visa, are treated as cash in most shops.
When it comes to average costs, much depends on where you've chosen to go. A jaunt around the barbeque shacks of Texas and the Deep South won't cost you much in accommodation, dining, or souvenir-buying, but gas prices will add to the expense. By contrast, getting around a centralized city such as Boston, New York, or Chicago will be relatively cheap, but you'll pay much more for your hotel, meals, and shopping purchases. Also keep in mind that added to the cost of most items you purchase is a state – but not federal – sales tax, anywhere from less than three percent (in Colorado) to more than eight percent (in New York), and big cities may add on another point or two to that rate. (Alaska, Delaware, Montana, New Hampshire, and Oregon have no state sales tax.) Additionally, some cities – probably the ones you most want to visit – tack on a hotel tax that makes the total tax for accommodation around fifteen percent.
Unless you're camping or staying in a hostel, accommodation will be your greatest expense while in the US. Adequate lodging is rarely available for under $60, outside of bare-bones roadside motels and off-season cabins. A halfway decent room will run anywhere from $75–100, with fancier hotels costing much, much more – upwards of $200–350 in many of the big cities.
Unlike accommodation, prices for good food don't automatically take a bite out of your wallet, and you can indulge anywhere from the lowliest (but still scrumptious) burger shack to the chicest restaurant helmed by a celebrity chef. You can get by on as little as $20 a day, but realistically you should aim for around $50–60.
Public transit options are usually affordable, with the best deals being the multi-day or week-long transit passes offered by most cities for riding on buses, light rail, and subways. Renting a car, at around $120–200 per week, is a far more efficient way to explore the broader part of the country, and, for a group of two or more, it's no more expensive, either. Keep in mind, though, that for those under 25 years of age, there are often supplements of $20 a day tacked onto car rental fees.
Tipping is expected for all bar and restaurant service. Expect to tip about fifteen percent of the bill before tax to waiters in most restaurants (unless the service is truly wretched), and twenty percent for good service. Tips are where most of a waiter's income comes from, and not leaving a fair amount is seen as an insult. About fifteen percent should also be added to taxi fares; round up to the nearest 50¢ or dollar, as well. A hotel porter should get $1–2 per bag; if he's lugged your suitcases up several flights of stairs, make it $3–5. Chambermaids get $1–2 per guest for each day; valet attendants get $2.