Coming from Oz, where a full 50% is Taxes (erm, sorry, 40% is excises, and 10% is taxes (4% of which is a tax on an excise)), the retail companies are screwing us.
When our dollar was 45cUS, Oil was $37US per BBL and petrol hit $1.00 per litre, it was all explained, by the Government that 1cUS drop in our dollar, OR $1US per BBL increase would cost us 1cOz per litre at the bowser.
Now, we are at $75cUS, and Oil is (say) $50 per BBL.
Our petrol prices should be $1.00 - $0.25 + $0.13, or 88cOz per litre.
"Competition", and the increase of cheaper outlets (owned by the majors) have managed to bring our petrol down to 97c.