Write a function to calculate compound tax using the following table:

For $10 and under, the tax rate should be 10%.
For $20 and under, the tax rate on the first $10 is %10, and the tax on the rest is 7%.
For $30 and under, the tax rate on the first $10 is still %10, the rate for the next $10 is still 7%, and everything else is 5%.
Tack on an additional 3% for the portion of the total above $30.
Return 0 for invalid input(anything that's not a positive real number).


Examples:

An input of 10, should return 1 (1 is 10% of 10)
An input of 21, should return 1.75 (10% of 10 + 7% of 10 + 5% of 1)

* Note that the returned value should be rounded to the nearest penny.

```python

USER_FILENAME = "<user_code>"
import sys, json, builtins
import math, heapq, bisect, itertools, functools, collections, statistics, fractions, decimal, operator, array, random, re, string, os, pathlib
try:
    import resource as _res
except Exception:
    _res = None
from collections import Counter, defaultdict, deque, OrderedDict
from functools import lru_cache, reduce
from itertools import accumulate, permutations, combinations, product
from math import gcd, ceil, floor, sqrt
from decimal import Decimal
try:
    from typing import *
except Exception:
    pass
try:
    sys.setrecursionlimit(1_000_000)
except Exception:
    pass
try:
    import site as _site
    try:
        _sys_sites = _site.getsitepackages() if hasattr(_site, "getsitepackages") else []
        for _p in _sys_sites:
            if _p and _p not in sys.path:
                sys.path.append(_p)
    except Exception:
        pass
    try:
        _usp = _site.getusersitepackages()
        if isinstance(_usp, str):
            _usp = [_usp]
        for _p in _usp:
            if _p and _p not in sys.path:
                sys.path.append(_p)
    except Exception:
        pass
except Exception:
    pass

def _disabled_input(*args, **kwargs):
    raise RuntimeError("input() is disabled in callable mode")
builtins.input = _disabled_input

ns = {"__name__": "__judge__"}  # prevent if __name__ == "__main__" blocks
for _k, _v in list(globals().items()):
    if not _k.startswith("_"):
        ns[_k] = _v
_CODE = 'from numbers import Real\n\n\nclass TaxCalculator(object):\n    def __init__(self, bands, highest_rate):\n        self.__table = list(self._get_table(bands, highest_rate))\n\n    @staticmethod\n    def _get_table(bands, highest_rate):\n        lower_bound, cumulative_tax = 0.0, 0.0\n        for upper_bound, rate in bands:\n            yield lower_bound, rate, cumulative_tax\n            cumulative_tax += (upper_bound - lower_bound) * rate\n            lower_bound = upper_bound\n        yield lower_bound, highest_rate, cumulative_tax\n\n    def __call__(self, amount):\n        if isinstance(amount, Real):\n            for lower_bound, rate, cumulative_tax in reversed(self.__table):\n                if amount >= lower_bound:\n                    return round((amount - lower_bound) * rate + cumulative_tax, 2)\n        return 0.0\n\n\ntax_calculator = TaxCalculator([(10.0, 0.10), (20.0, 0.07), (30.0, 0.05)], 0.03)\n'
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

_target = None
_fn_name = 'tax_calculator'
if _fn_name:
    if "Solution" in ns:
        try:
            _obj = ns["Solution"]()
            if hasattr(_obj, _fn_name):
                _target = getattr(_obj, _fn_name)
        except Exception:
            _target = None
    if _target is None and _fn_name in ns and callable(ns[_fn_name]):
        _target = ns[_fn_name]
# Fallback: if there's exactly one user-defined function, use it
if _target is None:
    _cands = [v for k, v in ns.items() if callable(v) and getattr(v, "__module__", "") in ("__judge__", "__main__")]
    _user_funcs = [c for c in _cands if getattr(c, "__name__", "").startswith("_") is False]
    if len(_user_funcs) == 1:
        _target = _user_funcs[0]
if _target is None:
    raise RuntimeError(f"Could not resolve callable '{_fn_name}'")

_raw = sys.stdin.read().strip()
if _raw:
    _parsed = json.loads(_raw)
    if isinstance(_parsed, dict):
        _kwargs = _parsed.get("kwargs", {})
        _args = _parsed.get("args", [])
    else:
        _args, _kwargs = _parsed, {}
else:
    _args, _kwargs = [], {}
if not isinstance(_args, (list, tuple)):
    _args = [_args]
_res = _target(*_args, **_kwargs)
try:
    sys.stdout.write(repr(_res) + "\n")
except Exception:
    pass

```

Measured memory_bytes: 6622