Retail sales in the United States gained marginally on the week ending July 5, the International Council of Shopping Centers-USB reported Tuesday.Shopping gained by 0.2 percent on the week, but 2.3 percent from a year ago, the report said.Consumer spending continues to be adversely affected by high fuel prices that reduce discretionary purchasing power, the report said.The retail group noted that the national average gasoline prices rose by 1.9 cents to a record $4.114 per gallon on July 7. ...