Help with a banking Program

[buran]

It's an issue caused by floating point arithmetic
look also at https://docs.python.org/3/tutorial/floatingpoint.html

>>> deposit = 1000.2
>>> withdrawal = 1000.1
>>> balance = deposit - withdrawal
>>> balance
0.10000000000002274
>>> print('{:.2f}'.format(balance))
0.10
>>> print(f'{balance:.2f}')
0.10
>>>

one way to deal with it (sufficient at least for homework purposes) is to use string formatting - f-strings or str.format() method so that you represent the result, being float, up to 2 decimal places precision

In real life, when dealing with number representing money amounts one would make sure to always work with correct precision, so that there is no artefacts like extra cent due to rounding accumulated over time. One way is to use decimal module

>>> from decimal import Decimal
>>> deposit = Decimal('1000.2')
>>> withdrawal = Decimal('1000.1')
>>> balance = deposit - withdrawal
>>> balance
Decimal('0.1')
>>> print(balance)
0.1