ISSAQUAH, Wash. — Costco had net sales of $11.43 billion in July. The four weeks ended August 4, 2019 with an increase of 7.9% from $10.59 billion last year. For the 48-week year to date, the company reported net sales of $137.56 billion, up 8%. Comp sales for the month were up 5.6% and up 6.2% year-to-date.