```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!
```
def fuel_price(litres, price):
    if litres <2:
        return round(litres * price, 2)
    elif litres <4:
        return round(litres * (price-0.05),2)
    elif litres <6:
        return round(litres * (price-0.1),2)
    elif litres <8:
        return round(litres * (price-0.15),2)
    elif litres <10:
        return round(litres * (price-0.2),2)
    else:
        return round(litres * (price-0.25),2)
def fuel_price(litres, price):
    if litres <2:
        return round(litres * price, 2)
    elif litres <4:
        return round(litres * (price-0.05),2)
    elif litres <6:
        return round(litres * (price-0.1),2)
    elif litres <8:
        return round(litres * (price-0.15),2)
    elif litres <10:
        return round(litres * (price-0.2),2)
    else:
        return round(litres * (price-0.25),2)