First of all, dodge can never reach 100%. I don't know what the dexterity cap to scaling is, but even if it were at 90%, you still could not reach 100% dodge no matter what you did. Secondly, dodge does not stack additively. This goes hand-in-hand with the first rule. If it did, you would quickly reach over 100% dodge and that quite frankly is impossible. And lastly, dodge bonuses do not stack by generic multiplicity for the same reasons they don't stack additively. If you could increase your dodge by 30%, then you'd only need ~77% to reach 100% dodge (~0.77 * 1.3 = 1.00). So that begs the question...
How does Dodge stack?
First of all, to answer this we really need to shift our focus from a "chance to dodge" to a "chance to be hit." If you have 30% dodge, then you have a 70% chance to be hit. Pretty simple right? (100% - 30% = 70%) This is a really important factor because your chance to be hit does stack multiplicatively, meaning you simply multiply all these chances together to find out the total chance to be hit.
Let's do an example real quick. First, we'll assume we have a base of 35% dodge and we want to know what our bonus is when Mantra of Evasion is up and then we'll add to that for when we are attacking with the Fists of Thunder: Lightning Flash rune.
So we'll start out with base dodge:
1) 35% dodge = 65% chance to be hit.
Mantra of Evasion has a 15% dodge bonus:
2) 15% dodge = 85% chance to be hit.
Our total chance to be hit with our base dodge and our Mantra of Evasion up then becomes:
3) 0.35 * 0.85 = 0.5525 or 55.25%
We need to convert that back to "Dodge Chance" if you really want to know that total so:
100% - 55.25% = 44.75%
For all bonuses, they stack in the same way. To find what it is while attack with Fists of Thunder (16% dodge or 84% chance to be hit), we'll just re-do step 3:
3) 0.35 * 0.85 * 0.84 = 46.41% chance to be hit or 53.59% Dodge chance
If you have more effects, (say those of Cyclone Strike or whatever), you would just keep stacking them into step 3. Why do they do this you may ask? Well, there is no way to make your dodge reach 100% this way. It is mathematically impossible and they don't want people to be able to dodge every attack and become essentially invincible.
I hope this clears some of the confusion because the wording in the abilities does not make the workings of this mechanics very obvious. In fact, I'd say the wording is the most confusing part about it.