Starting in 1989, France minted several different commemorative 5 franc coins in copper-nickel, silver, and gold. Miles has the 1992 version with Pierre Mendes. It was under the government of Mendès that France withdrew its military forces from Vietnam in 1954.
The value of these coins depends on the amount of precious metal they contain.
COPPER-NICKEL: no precious metal
SILVER: 0.347 troy ounces
GOLD: 0.414 troy ounces
A copper-nickel coin is worth 5 francs plus zero. A silver coin is worth 5 francs plus the value of 0.347 troy ounces of silver. A gold coin is worth 5 francs plus the value of 0.414 troy ounces of gold.
To find the current value of gold and silver, use web sites such as kitco.com. These values change every day, so look them up. At the time of this revision, silver is worth $16.50 US dollars per troy ounce, and gold is worth $1205 US dollars per troy ounce.
Sometimes salesmen will try to tell you that the silver and gold coins are worth more than the precious metal they contain. Don't believe them. If you have one of these coins for sale, all you will be able to get is the value of the precious metal. The fancy packaging and official-looking certificates are worth nothing.