$100, a bank will only give you face value, take it to a coin dealer.
On the 5 dollar bill: Redeemable in gold on demand at the united states treasury or in gold or lawful money at any federal reserve bank. 1928 series A A.W. Mellon secretary of the treasury
There aren't any U.S. government $5 gold certificates. It's possible you have something issued by a private bank. Please post a new question with a more complete description.
All 1928 $5 Federal Reserve Notes carried the phrase "Redeemable in Gold", although they weren't gold certificates and in fact no gold certificates with that denomination were printed. Please see the question "What is the value of a 1928 A US 5 dollar Federal Reserve Note?" for more information.
The only $5 bills redeemable in gold were National Gold Bank Notes printed in the early 1870s. If that's what you have, it should be examined in person by a reputable currency dealer because these items are considered to be moderately rare. Values as of 02/2011 range from $1000 for a very worn specimen to nearly $9,000 for one that's in nearly new condition.
If very worn, $250; if nearly new, $750.
On the 5 dollar bill: Redeemable in gold on demand at the united states treasury or in gold or lawful money at any federal reserve bank. 1928 series A A.W. Mellon secretary of the treasury
Need more information - date, bank of issue (if applicable), design, condition for starters.
A 1928 $50 bill that is redeemable in gold on demand is known as a Gold Certificate. These certificates were issued during a time when the US dollar was backed by gold. As a collectible item, the value of the bill would depend on factors such as its condition and rarity. They can be worth more than their face value to collectors and currency enthusiasts.
In the US there are no gold dollar bills.
There aren't any U.S. government $5 gold certificates. It's possible you have something issued by a private bank. Please post a new question with a more complete description.
All 1928 $5 Federal Reserve Notes carried the phrase "Redeemable in Gold", although they weren't gold certificates and in fact no gold certificates with that denomination were printed. Please see the question "What is the value of a 1928 A US 5 dollar Federal Reserve Note?" for more information.
All 1928 $5 Federal Reserve Notes carried the phrase "Redeemable in Gold", but they weren't gold certificates and in fact no gold certificates with that denomination were printed. In addition, the bill was distributed by the Federal Reserve Bank located in Cleveland; it wasn't produced by a bank called the Bank of Cleveland. Please see the question "What is the value of a 1928 US 5 dollar Federal Reserve Note?" for more information.
The only $5 bills redeemable in gold were National Gold Bank Notes printed in the early 1870s. If that's what you have, it should be examined in person by a reputable currency dealer because these items are considered to be moderately rare. Values as of 02/2011 range from $1000 for a very worn specimen to nearly $9,000 for one that's in nearly new condition.
If very worn, $250; if nearly new, $750.
The phrase "redeemable in gold" indicates your bill was printed before 1933, but a specific date and series letter are needed. Please post a new question with its date and what letter if any is next to the date.
All 1928 $100 FRNs carried the wording that they were redeemable in gold. There's more information at the Related Question.
The worth of a 1928 fifty dollar bill redeemable in gold on demand in very fine to AU condition will vary. You will need to take it to a collector, or someone who can appraise money. Without actually seeing it, it is hard to put a price on it.