Long ago, the common folk traded goods and services using a coin known as a bit.
A bit was one eighth of a larger coin known as pieces-of-eight. Get it? Pieces-of-eight were worth 8 bits. The most common pieces-of-eight coin was the Spanish Dollar.
In computer programming, a bit is a single on/off switch. Eight bits combine to make a byte which is the standard measurement of storage capacity.
In colonial days, a bit was a substantial piece of currency. One might buy a pint of ale for a bit, a meal for two bits and a cheap hotel for four bits.
On passage of the Coinage Act of 1792, the mint weighed a number of the worn and shaved Spanish dollars circulating in the colonies and set that weight in silver (412.5 grains) as the United State's dollar. The US dollar was made of a 90% silver 10% copper mix. It became customary to denote the dollar with the symbol $.
The Coinage Act sought to create a decimal system for currency calculations. The act created a monetary system with silver dollars, silver quarters and silver halves along with strange new coins called the disme, a half disme and penny. The copper penny was valued at one percent of a silver dollar. The disme (commonly known as a dime) was set at a tenth of a dollar.
The quarter and half dollar fit into common reckoning well. The quarter was worth two bits. The half was worth four bits. The bit coin itself was problematic. A bit was worth 12.5 cents. Proprietors of the day were known to accept the new disme as a short bit and to accept the loss of the odd bit as cost of doing business.
The Spanish dollar was recognized as legal tender in the US up to 1857. The system of reckoning in bits existed alongside the new dollar system for quite some time.
In the round down program, I suggest that proprietors of today round down cash transactions to the nearest quarter (the two bit coin).
Today's quarter is worth substantially less than the two bit coin of old. A silver quarter sells on ebay for about $7.00. While the deflated quarter in your pocket is only worth a penny candy, the old two bit could still buy a meal.