Praise be to Allaah.
It is not permissible to sell haraam things such as cigarettes, promiscuous magazines or magazines that promote evil, even if they are published by Muslims, because when Allaah forbids a thing He also forbids its price. It is not permissible to work for these magazines because this is a kind of cooperating in sin and transgression. The income from such sales is haraam. A person has to fear Allaah with regard to his food and drink and all his spending. Selling gas is permissible, and there is nothing wrong with it. If the taxes are compulsory then the one who is forced to do a thing will be forgiven.