You can just do calculations with floats as much as possible, e.g., 15% = 0.15, binary search with epsilon = 0.0001.

Rounding with round(x, 2) are needed only when:
 1. K*L
 2. output of T(K)
-- "The calculation of the regional coefficient and all kinds the taxes is made with rounding off to two digits after a decimal point."

while K itself is float.

A test like this is possible:
15
0 35
12000000
12000000
-1

First time it occurs in Test 9.
This means that you should pay the same tax for any amount of salary. It is ok to output 0.00 for all such tests, despite it is not correct always because of interim roundings of regional coefficient.
Everything else is well-described in previous comments, basically correct numbers round and correct searching of initial salary (you should search for max possible value with 2 decimal places in it) are the only things that can make the initial problem description being unclear.

I apply rounding (as floor(x*100+0.5)/100)
only to RESULT of T(R) and to regional coefficient. But I can't pass test 7. Can anybody help me?

In this problem we need to calculate R(S): F(R) = S,
where F(R) = R – T(R) + L%*R – T(L%*R).
But function F(R) is NOT increase monotonically!
In other words, it is possible to find R: F(R) = F(R+1).
So, it is impossible to calculate unique R(S).

Example:
99
1000000000 10
2000000000 40
3000000000 41
0          77
100000000
2000000000
3000000000
4200000000
5000000000
1100000001
2200000000
3300000001
-1

If in your program R(S) = max{R: F(R) = S}
then answer = 11086345330.78
(and you'll get AC)

If in your program R(S) = min{R: F(R) = S}
then answer = 11086345330.81
(and you'll get WA #7)

Also your program can write another answers.
Which of they are correct? And why?

i can't understand, why, where, and how
I must round intermediate results.
I try it all, but got WA on test 1..3

please help me!!!

or you can send me AC program,
that i may understand this condition.

Please, throw the decision these are problems on e-mail: ufo.nix@mail.ru
Would make itself, but now a blockage on study... I am not in time..:-(

What is it?
I first got it.

And what do with it?
If you whant I can give you my code
mailto: tolik-tol@inbox.ru

The algo is easy, but you must read the problem's description very carefully, and take care of rounding: r = int(r * 100 + 0.5) / 100, use it when calc tax and add up...

Because of rounding, it takes me almost one day to AC this problem...:(

my source:
(Pascal)
begin
end.
I need get WA1, but I get WA2.
What is it? A bug?

My program always wrong, but I don't know why, if you got
AC, can you send me your program?

I do not understand how the rounding occurs.
First of all is it a floor(x*100)/100 (trunc-like) or a floor(x*100+0.5)/100 (round-like)?
When does it occur? At any operation other than addition?
For example, when computing the taxes for some value, the result is rounded at every segment (where percentage is applied) or only after the summation? When computing T(R*L%), R*L% is rounded before computations or not?
The gross profit for each enterprise (the one we have to compute) is also with only 2 decimals?

I guess it is obvious that the sample and some of the test are COMPLETELY WRONG. Does anybody have an idea where does the sample answer come from? Any ideas that you'd like to share?