If by manipulated, you mean providing all available data to investors, then yeah, I guess so. CVS is refusing full disclosure based on the reasoning that if investors know whats' going on, they'll sell. :-)
Critics of monthly sales say the reports have lost significance as an economic barometer in that they are no longer an accurate representation of the way consumers shop. For one, they don’t include online sales, a fast-growing category for many retailers. Also, gift cards, another growing trend, are not counted as sales until they are redeemed. And some retailers have said they stopped releasing their monthly numbers because the announcements provoked volatility in their share prices.