[whynotmaybe]

Both will be used more, the issue with the nickel is that it costs around 14¢ to make one.

[sgerenser]

I'd have to see a mathematical proof as to why nickels or dimes would be used more, I don't actually think that's the case.

[svachalek]

The only logical argument I can imagine is that people are using stacks of 5 pennies now routinely instead of nickels. But personally I never see that happening.