Excel Rounding Problems

Hi

I am trying to produce a set of figures in column B for a a set in column A.
The figure produce in Column B should be determine on preset conditons
If A<80%, B=0
If A>100%, B=20
If 80<=A<=100%, B= A-80%

All of set in A are positive percentages
The figure should then be *100 and then rounded down to the closest integer.

I have been using
"=INT((IF(A1>1, 0.2, (IF(80%<=A1, A1-0.8, 0)))*100))"

A B
0.75 0
0.76 0
0.77 0
0.78 0
0.79 0
0.8 0
0.81 1
0.82 1
0.83 2
0.84 3
0.85 4
0.86 5
0.87 6
0.88 8
0.89 9
0.9 10

As you can see there appears to be rounding issues possibly made during the calculations that is affection 0.82-0.87.
Would anybody be able to advise on this or produce an alternative formula for the same thing?

Thanks