I don't understand your objection. The cost includes all tax.

Suppose the following price breakdown for a pack of cigarettes:

    cost: $3
    profit: $1
    tax: $1
    total price: $5

The government decides to increase the tax by $1, now it's

    cost: $3
    profit: $1
    tax: $2
    total price: $6

As you can see, the total price went up $1, but the tobacco company's per-unit profit is the same. They can increase the price by more than the tax (eg. hiking the price by $1.5 rather than $1), but that's equivalent to hiking the price $0.5 without an associated tax increase, which they can do at any time.

Let's say a competitor shows up who manufactures cigarettes at $1.

At a lower tax rate of $1 his cigarette is $3 vs $5.

But at a higher tax rate of $3, it is a $5 vs $7 customer price.

In absolute terms the price difference is the same. However, consumers think in terms of percentages for cheaper items.

Any added margin that makes your product more expensive, that does not go into your pocket, is bad for business.

It's basically a form of someone stealing from you.

The user was willing to pay $4.50, all of which you could have had, but $0.50 went to a parasitic third party.

We can look at it from the point of view of the transaction between the buyer and seller being arbitrarily robbed of $0.50.

We can also look at it from the POV of the supply-demand curve: fewer units are sold of the more expensive product.

Both these effects hit you: you're selling less because it's more expensive, without you getting any more of the extra per-unit revenue.