Question

آن فروشنده هوای من رو داشت و تخفیف خوبی به من داد

Answer 1

He was kind enough to give me a good discount.

Example: 

The doctor was kind enough to give me a discount.

https://goo.gl/uz3AN7

He did me a favor by giving me a good discount.

Example: http://goo.gl/VQK0Yb

Answer 2

The salesman was very nice to me and gave me a good deal.

Comments

... gave me a good deal 

is correct

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North American way of saying it is "good deal" .

Good discount is also correct, but good deal is more popular :) 

Answer 3

The salesman cared about / considered my budget / pocket and gave me a good discount.

The salesman backed up my pocket and gave me a good discount.

 

Comments

What if I say

He had my back and gave me a good discount?

 

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In my view , it's OK too.

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+1 I like "The salesman backed up my pocket" or even "backed me up".

So I would say another answer would be 

The salesman backed up my pocket and gave me a good deal