Please check your bill again and post a new, separate question. The US didn't print any bills dated 1968.
There were no 1968 Australian Five Dollar notes printed.
One dollar in 1968 was worth the same as $6.58 cents today. The dollar is no longer worth as much because of inflation.
There is no such thing as a 1968 Franklin halfdollar. But there is a John F. Kennedy half dollar from 1968.
Turn the coin over and check the denomination on the back. It's a 50 cent piece, not a dollar. The U.S. did not make any dollar coins in 1968.
Please take another look at your bill. It can't be as described for several reasons:There are no 1950 $2 bills. The nearest date is 1953,$2 bills weren't printed as Federal Reserve Notes until 1976. From 1928 to 1963 they were issued as red-seal United States Notes.Federal Reserve Notes have never been exchangeable for silver. That was possible with silver certificates, a third form of paper money printed until the 1957 series of $1 bills. Redemption for silver was discontinued back in 1968.
It is made of 40% silver and has a melt value of about $2.50 as of 08/2008
No US silver dollars were made after 1935, look at the back of the coin for 'Half Dollar'.
Starting in 1968, Canadian dimes, quarters, half dollars, and dollars were all made of nickel, not silver. It's worth one dollar in Canada.
The US didn't make any 1968 commemorative halves, only standard-issue Kennedy halves.
The coin is a 40% silver Kennedy half dollar most are valued only for the silver, about $6.00
The U.S. did not print any $10 bills with that date.
They're worth about $2.50 a piece for the silver.