I don't know the origin of dozen but counting in multiples of 10, i.e., the metric system is a very recent phenomenon. If you go to America, you will find that there are many things that are measured there which are not in metric system. e.g. Volume is measured in gallons. 1 gallon = 4 quarts. 1 quart = 32 ounces or 2 pints. Distance is measured in miles. 1 mile = 1760 yards. In India also, land is not measured in metric system, but a different system. Our currency was not divided into hundred parts. British had a system similar to current American system, but they slowly moved to metric system. American system still clings on, though.