Egyptian-esque Currency
It might be useful to simplify the Egyptian-esque economy to three units:
• "gold" ≈ Duben ≈ 1000 gp
• "copper" ≈ Senyu ≈ 1 gp
• "loaf" ≈ 1 cp
But for Egypt-esque flavor never actually use money. Always trade one item or service for an other item or service.
Reallife Egyptian currency is something like the following.
Normally, people simply trade a good or service directly, in an adhoc bartering system. They go to a public marketing area, weekly and seasonally, and exchange things they have or can do for other things they need or need done.
However, loaves of bread and ceramic jars of beer can come in standard sizes that can work like coins. The beer is made from baked beer-bread of wheat/barley, soaked and mashed in water to brew with dates, honey, and spices. A ‘beer jar’ is roughly 2 liters (half gallon) depending on the standard of the place and time. Beer and bread are the staple of the Egyptian diet. So, one could either eat the money or trade it for goods or services of an equivalent value.
For bartering costly items, the wealthy (royalty, priesthoods, technological crafters, merchants) measure the value of a costly item in terms of how much gold it would be worth. But they never actually use the gold itself as money. Instead, they would trade the costly item in exchange for one or more goods or services that would total the worth of about the same amount of gold.
Gold was the standard unit of value, but never actually used as money. There are standard units of weight for gold. About 7.5 grams of gold is called a Shat. Twelve Shats being about 90 grams of gold is called a Duben. There is also mention of using these same units of weight to weigh copper (Senyu 7.5 g and Dubenture 90g). Gold is worth about 166 times the same amount of copper, during Dynasty 18 and 19, and about 120 times later on. Silver is worth roughly twice as much. The Duben of gold comes to be the main standard of measurement.
Archeologists speculate that Egyptians never actually used money because gold was divine, magically imbuing immortality and indestructibility, thus was too holy for profane people to touch. Meanwhile, silver was also holy, but too rare anyway.
Actual coins dont come into existence in Egypt until the Classical Age, from the Persian Period onward. And from the Hellenistic Period onward is moreorless identical with Greek and Roman currency, except Egyptians would still tend to use units of grain as the currency locally.
For an Egypt-esque game.
Measure the worth of daily stuff in terms of how many bread loaves it is worth. Measure costly stuff in terms of how much gold it is worth.
Copper is never used for money or a unit of value, but is listed here because the bronze tools, weapons and armors are made out of copper (alloyed with tin).
In other words, D&D player characters can know how much a magic item is worth in gold. Each 1000 gp is a Duben, the standard amount of gold. Nevertheless, an item can only be exchanged for an other magic item of equal worth, or else for a combination of items, jobs, or a quest whose total is of equal worth.
Most gold is actually electrum, so treat gold and electrum as the same thing, but during Dynasties 18 thru 20, pure silver is worth about half as much as gold.
Egyptian-esque commodity ≈ D&D gp
• gold standard (Duben) ≈ 1000 gp
• gold standard (Shat) ≈ 100 gp
• copper standard (Dubenture) ≈ 10 gp
• copper standard (Senyu) ≈ 1 gp
• beer jar ≈ 10 cp
• bread loaf ≈ 1 cp
It might be useful to simplify everything down to three units:
• "gold" ≈ Duben ≈ 1000 gp
• "copper" ≈ Senyu ≈ 1 gp
• "loaf" ≈ 1 cp
For Egypt-esque flavor never actually use money. Always trade one item or service for an other item or service.