Rule of Thumb:

To calculate dollars "accurately" with 2 decimal places, you need
to calculate right from the beginning in cents as integers!

So just calculate with integers in the desired accuracy and shift the decimal point afterwards²!

Background:

Floats are not accurate with decimal fractions because the computer "has only two fingers".

Experiment

Just try to express 1/3 accurately in decimal system!

And now imagine you're an alien with 3 fingers 4 and you have only computers that calculate in decimal fractions¹... wouldn't this annoy you, too?

Conclusion

Humans have too many fingers! Downsizing³ to octal system would do it...

Cheers Rolf

Footnotes:

In reply to Humans have too many fingers by LanX
in thread perl floating number addition by adismaug

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