In 1966, coins were introduced in denominations of 1, 2, 5, 10, 20 and 50 cents. The initial 50-cent coins contained 80% silver and were withdrawn after a year when the intrinsic value of the silver content was found to considerably exceed the face value of the coins. One-dollar coins were introduced in 1984, followed by two-dollar coins in 1988 to replace the banknotes of that value, while the one- and two-cent coins were discontinued in 1991 and withdrawn from circulation. In commemoration of the 40th anniversary of decimal currency, the 2006 mint proof and uncirculated sets included one- and two-cent coins. In early 2013, Australia's first triangular coin was introduced to mark the 25th anniversary of the opening of Parliament House. The silver $5 coin is 99. 9% silver, and depicts Parliament House as viewed from one of its courtyards. Cash transactions are rounded to the nearest five cents. As with most public changes to currency systems, there has been a great amount of seignorage of the discontinued coins. All coins portray the reigning Australian Sovereign, Queen Elizabeth II, on the obverse, and are produced by the Royal Australian Mint.