Is it legal for one tennant to pay 95 percent of the rent and the other tenant to pay 5 percent of the rent?

Short answer?  Yes.

If you are both on the same rental contract, you are jointly responsible for paying 100% of the rent.  The landlord doesn't care how you split it up.

That being said, the one paying 5% should cover their butt by having a signed roommate agreement stating that both agree to such an arrangement.   If the roommate paying 95% decides to sue the other roommate for not paying their half, the roommate agreement could be shown to the judge.

There is no law that says roommates much share the rent 50/50, but in the case of a dispute, it's reasonable for a judge to decide that two adults sharing an apartment also share the cost of rent (unless there is proof the roommates agreed to split it a different way). 

Yes, adults can agree to handle their business dealings that way.  I know some deals in which one tenant pays NOTHING and the other covers the bills and the rent. All completely legal.

Legal?  Of course.  It's no different than going out to pizza with friends and splitting up the bill however you want.  

Every once in awhile there are questions which just blow my mind as to the mindset of some people to even think something may be true.  

Of course it's legal.

The landlord only cares that the rent is paid in full and on time every month. He doesn't care how the tenants split the rent.

Yes. There are no laws on how roommates split the rent. 

Whatever the two of you agree on is legal for the split of the rent.

Any arrangement you make with your roommate on how to split the rent is legal.