Solve the programming task below in a Python markdown code block.
```if:python,php
In this kata you will have to write a function that takes `litres` and `price_per_litre` as arguments. Purchases of 2 or more litres get a discount of 5 cents per litre, purchases of 4 or more litres get a discount of 10 cents per litre, and so on every two litres, up to a maximum discount of 25 cents per litre. But total discount per litre cannot be more than 25 cents. Return the toal cost rounded to 2 decimal places. Also you can guess that there will not be negative or non-numeric inputs.

Good Luck!
```

```if:csharp,java,javascript
In this kata you will have to write a function that takes `litres` and `pricePerLitre` as arguments. Purchases of 2 or more litres get a discount of 5 cents per litre, purchases of 4 or more litres get a discount of 10 cents per litre, and so on every two litres, up to a maximum discount of 25 cents per litre. But total discount per litre cannot be more than 25 cents. Return the toal cost rounded to 2 decimal places. Also you can guess that there will not be negative or non-numeric inputs.

Good Luck!
```
Also feel free to reuse/extend the following starter code:
```python
def fuel_price(litres, price_per_liter):
```