A more accurate alternative might be to use integer arithmetic:

$ perl -E '$c = -71123456; for my $i (0..19) {say $c/1000000; $c += 10
+000}'
-71.123456
-71.113456
-71.103456
-71.093456
-71.083456
-71.073456
-71.063456
-71.053456
-71.043456
-71.033456
-71.023456
-71.013456
-71.003456
-70.993456
-70.983456
-70.973456
-70.963456
-70.953456
-70.943456
-70.933456
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You might also consider using the arbitrary big rational number module (Math::BigRat) or possibly the big float module (Math::BigFloat).

Math::BigRat is accurate because it basically does integer arithmetic under the hood.