Simple DC voltage scaling with two ranges, lower range voltage limited
A zener isn't really the answer here, but that doesn't mean diodes aren't the way:



I'm assuming your 5V inputs are going into an ATmega (e.g. arduino) or similar device, where the 5V limit isn't really exactly 5V, but rather "enough above 5V to turn on the protection diodes". In this case, the circuit shown above will work fine.

Caveats are: 


Your 5V device needs to be able to sink a ~4.5 mA into the 5V rail (an arduino will do this fine), or the voltage divider will actually cause the 5V rail to increase.
You must use schottky diodes for the diodes. You need your diodes to turn on before the MCU's internal diodes.
The lower two diodes are really extra. They prevent the ADC inputs from going below ground if the input voltage goes below 0V. I don't know if that's a possibility in you application, but it's cheap insurance.