They were unusual tax shelters that went by incomprehensible names like BLIPS, OPIS, BOSS and FLIP — and they boomeranged on the companies that sold them. In February, German bank HVB Group agreed to pay $29.6 million in fines to avoid indictment for defrauding the Internal Revenue Service with abusive tax shelters that gave rich clients phony losses to reduce taxes. The settlement was part of a broadening investigation into exotic shelters that wealthy individuals used to escape about $2.5 billion in taxes from the mid-1990s through 2003, according to the government. Indeed, the IRS recently announced that a string of law firms, banks and accounting firms will be fined billions of dollars for failing to admit their role in promoting these improper investments. Last fall, KPMG LLP, the accounting firm that created and marketed many of the shelters, agreed to pay $465 million to avoid indictment.…