It is ok to put “quand même” before “jamais”.

But, I would say either

Tu ne comprendras quand même jamais.

or

Tu ne comprendrais quand même pas.

If you want to be a little more sustained, you can also use “Tu ne comprendras donc jamais.”

“Tu ne comprendrais quand même jamais.”

Is incorrect in French, I would rather say:

“Tu ne comprendras donc jamais.”

That can be translated as:

So you’ll never understand.

Not sure why other answers consider the conditional mood incorrect here but your sentence is just fine:

Tu ne comprendrais quand même jamais.

Alternatives can be:

De toute façon, tu ne comprendrais jamais.

Malgré tout, tu ne comprendrais jamais.

“Quand même” expresses the disregard of a condition, order, principle, etc. that has been previously stated, the happening of something in spite of adversity, contrary conditions, etc. “Donc” cannot be assimilated with “quand même” ;”donc” is a word meant to express a consequence. However, it’s perfectly correct to use “quand même” before “jamais”.

• Tu ne comprendrais quand même jamais.
  You wouldn’t ever understand anyway., You wouldn’t understand anyway, ever.

A good paraphrase for “quand même” is “de toute façon”, which rhymes well with the English “anyway”.

• Tu ne comprendrais de toute façon jamais.

There is the possibilité to front this adverbial locution or to reject it at the end after a comma ;

• De toute façon, tu ne comprendrais jamais. _ Tu ne comprendrais jamais, de toute façon