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Your final elif is missing a condition. Perhaps you meant to use else? As it is, your code will result in a SyntaxError.
Also, most of the conditions in your if clauses always evaluate to True, so none of the elif or else clauses will ever run. For example
if Type=="petrol" or "Petrol":
total=1.40*amount
There are two problems here: First, == has higher priority than or, so this will be interpeted as (Type=="petrol") or "Petrol"
Secondly, in python, a non-empty string (like “Petrol”) is considered to be True when used in a condition. Therefore, this code is equivalent to
if (Type=="petrol") or True:
total=1.40*amount
which will of course always run and never enter any elif or else clauses.
You should do something like this instead:
if Type in ["petrol", "Petrol"]:
total=1.40*amount
You should also consider adding some error handling, if for example the user enters “gasoline” or something else unexpected.