Money, Money, Money

Check it out.  These are some of the Australian coins.  They have a 5¢, 10¢, 20¢, 50¢, $1, $2.  Notice they don't have any pennies!  

"Notes" (in the U.S. we call them "bills") are made of plastic.  Each amount is a different size & color.  Also if you look close @ the picture you will notice a clear plastic symbol in a corner.  The smallest amount is a $5 note.  If you need $1, or $2 you need to use your coins.  
In America it is expected to tip most services.  For example if you get your car washed, hair cut or go out to eat, these are all things that you would tip for in America.  In Australia tipping isn't expected but always appreciated.  If you do choice to tip when you travel 10% is what is customary.  Here in America we're @ about 18%.

GST (sales tax) is included in the price of items you are buying.  GST stands for Goods and Service Tax.  Luxury Tax is an added tax that is placed on certain goods the government perceives as a "luxury".