Costco has seen a 5% increase in group sales in the first quarter. Reporting its Q1 financials, the US wholesaler declared that total sales for the 12 weeks to 24th November increased to US$24.47bn, up on the same period of last year when total sales came to US$23.3bn. The upturn was achieved despite foreign currency fluctuations and a decrease in the price of petrol, Just Food reports. Broken down geographically, …