Certainly, there is a correlation between sales and employment. [At least lagged a jth number of time periods.] Below are plotted the time series.
A 20% increase in sales correlates to a 4-5% increase in retail employment.
Figure 1: Retail employment, in thousands (blue, left scale), and real retail and food sales, in millions of 1982-84$ (red, right scale), both not seasonally adjusted. Sales (FRED series RSAFS) deflated by CPI-all. NBER defined recession dates, shaded gray. Source: BLS, FRED II, and NBER.
(Note that the sales figure includes auto and auto parts; sales ex.-auto constitutes about 82% of total, using seasonally adjusted data.)
http://www.econbrowser.com/archives/2010/12/hazards_in_inte.html
