No problem. The best types of businesses for this deal with a lot of cash, and are ideally service-based. If you are selling goods, then someone could investigate and find that you aren't buying enough supplies to account for your sales. For laundering millions, real-estate and fine art are popular, since you can buy it cheap, and then inflate it pretty arbitrarily, and sell it (to yourself or a coconspirator) for a huge 'profit'.