Retailers can expect holiday sales gains of 3.5% to 4% over the November through January sales period last year, according to a study by Deloitte LLP’s retail & distribution practice. Total sales should come in between $920 and $925 billion for the period, the accounting and market research firm stated.

The biggest gains, forecasts for between 15% and 17%, will be in non-store retail sales, Deloitte related, about three quarters of which are online.

Gas prices and the anticipation of promotions may hold holiday sales gains below last year’s 5.9%, Deloitte suggested. And the company asserted that retailers' digital connections with consumers are more critical this year.

"We anticipate retailers will come to the starting gate with true omni-channel pricing strategies, as opposed to disparate or reactionary strategies of the past," said Alison Paul, vice chairman, Deloitte LLP, and retail & distribution sector leader. "Consumers should see more price transparency across mobile, online and store channels, and retailers will use these same channels to gain insights into their core customers' behavior. Retailers that interpret and respond to real-time information about shoppers can hit the right notes on pricing and promotions that drive traffic without eroding margins."

Although smartphones now only influence about 5% of purchases, according to Deloitte, retailers who embrace their wired shoppers by offering mobile applications and wi-fi access actually are more likely to convert a visit to a sale. The company said shoppers armed with smartphones are 14% more likely to make a purchase in the stores the visit than those who do not use a smartphone as part of their in-store journey.

"Retailers that welcome the smartphone shopper in their stores with mobile applications and wi-fi access, rather than fear the showrooming effect, can be better positioned to accelerate their in-store sales this holiday season," said Paul. "The mobile channel is a powerful customer engagement tool, enabling retailers to capture a shopper's attention at the point-of-purchase, while gleaning valuable information about shopper behavior regardless of the shopper's location."