CHICAGO — Retailers appear to be becoming a bit more optimistic about sales and consumer spending although overall they remain cautious, a recent survey shows. Following a better-than-expected back-to-school season, retail chief financial officers surveyed by BDO USA here are projecting a 4.5% increase in total 2012 sales and a 3.6% gain in second-half comparable-store sales. While 57% of respondents in the BDO Retail Compass Survey of CFOs expect to see a continuation of stagnant economic conditions in the near future, the number of CFOs forecasting an ongoing economic turnaround nearly tripled this year (32%, up from 11% in 2011). Retailers are encouraged, said Doug Hart, partner in the retail and consumer product practice at BDO USA, but “forecasts are cautious as retailers closely watch unemployment, election results and inventory levels — any of which could throw a wrench in holiday results.”