Coupon and Discount result in different price behaviour (Hub 2.92)

Coupons are used for discounting price when applied.
Discount also provides discounting price when implemented.
However, a little difference was noticed when compared for same situation.
Here I will detail 2 different Scenarios (Price not including Tax, and including Tax)

Scenario: Price Include tax (5%): No
Example: price is $500 per room/night
Coupon provides 50% less price
Discount provides 50% less in price too.
Result:
First: Before Coupon and discount: $500


2nd: With 50% coupon only: $250


3rd: With 50% Discount Only: $237.50 (250 – tax(12.5)): Why tax is reduced now? But not with coupon.


4th: Coupon + Discount (50% each):
Coupon == > 50% ($250) then Discount == > ($125 : tax was reduced and it becomes: $118.75


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Scenario: Price Include tax (5%): Yes
Example: price is $500 per room/night
Coupon provides 50% less price
Discount provides 50% less in price too.

Result:
First: Before Coupon and discount: $467.19 (should b2 $475???) and way this price not including tax as expected.


2nd: With 50% coupon only: $238.10 (tax not included as expected)


3rd: With 50% Discount Only: $226.19 (238.10 – tax(11.91)): Why tax included now? But not with coupon.


4th: Coupon + Discount (50% each):
Coupon == > 50% ($238.10) then Discount == > ($119.05 : tax was reduced and it becomes: $113.10


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Consequently: manipulating tax with Discount is different from manipulating tax with coupon.
Final result, after full reservation provides same amount, I guess.