for One kata:

should not utilize JSON methods.
JSON methods are not allowed in this Kata
Unhandled rejection TestError: JSON methods are not allowed in this Kata

this is normal ?

If the author already made a test under Perl using sprintf "%.2f", then he should have taken into account that sprintf balances rounding. Engaging in guessing in which direction the number will be rounded is damn bad for the author.

Minus for the fact that the kata does not provide for checking other answer options, subject to the input conditions. For example '! ?? 'wrong, eh'!?? ' right. We have to guess by what scheme the author decided.