Adding One more condition to the formula

I have a Currency formula(This field is called Amount to Reimburse to Employee) that work perfectly fine now, however I will need to add more condition to this formula! I would like to say if [Category] equals to "Training" "Amount o Reimburse to To employee " should be 0.
I tried different ways but either it does not work or return formula error!

Any help would be really appreciated 

If([Category Requires # of 1-Way Trips Field],
If([Category - Multiplied by Mileage],
([# of 1-Way Trips] * [Category Rate]) * [Resource' Commuter Miles 1-way],
([# of 1-Way Trips] * [Category Rate])
),

[Mileage Cost]+[Cost]
)

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Michael Naser
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