Yes 10 is a good round number and that is why a lot of countries have gone over to decimal.Before industrialisation there very little standardisation and anthropic units of measurements were used. A foot was the length of (either an average person or the king's) actual foot. There is some confusion over the origin of the inch, some think it is from the Roman uncail meaning 12th part so it's one twelfth part of a foot others notice that in many other language (e.g. French, Swedish etc..) the same word is used for inch as is used for thumb but as it turns out the width of the average man's thumb measured at the base of the thumb nail was roughly 1/12th the length of the average man's foot.
Remember for everyday life in preindustrial society accurate measures on a scale we're used to weren't that necessary.
Not all countries throughout history have had 12 hour clocks, the ancient Egyptians for instance had 10 hours of daylight, 2 hours of twilight and 12 hours of night. However combining the 2 hours of twilight with the 10 hour day gives us our familiar 12 hours of day and night. There is some speculation as to why Egyptians counted in base 12 but it has influenced many cultures for centuries. One explanation is that we have three finger joints on our fingers so if we count our finger joints with our thumbs we can count to twelve on each hand. Mathematically 12 has more factors than 10 making it easier to sub-divide 12 than it is to subdivide 10.
Furthermore there are twelve astrological constellations that roughly divide the sky into 12 sections or astrological houses which the sun appears to pass through during a year. Many cultures are bound to have seen that. Furthermore the time it takes the sun to pass through one of those astrological houses is almost (but not exactly) the same as the time it takes the moon to go through a complete cycle, hence we have 12 months in a year, that is to say 12 moons (or 12 lunar cycles) in a typical year (although if you go by a lunar calender you tend to have 13 but that's because the time it takes the earth to complete one orbit round the sun is not an integer multiple of the number of times it takes the moon to orbit the earth).
