In the US, “two bits” means 25¢, though the US Mint has never produced a 12.5 cent coin. However, Brits have long called a low-value coin a “bit,” and in the US the term was applied to some early Mexican and Spanish coins in circulation which were valued at 1/8 peso, or about 12.5¢ at the time.
“A penny saved is a penny earned” is one of many wise maxims often credited to Benjamin Franklin, though he never actually said it. He came close with “A penny saved is a penny got,” and “a penny saved is two pence clear,” but these frugal notions were not original to Franklin; similar wisdom had been printed over a century before.
In physical size, a dime is the smallest circulating American coin. Hence, people say that a very quick-maneuvering vehicle can “turn on a dime,” as can a person who changes their own position on a subject quickly. The same idea is invoked by the expression “stop on a dime.”