TO TRICK A THIEF...YOU be the Sleuth

It's summertime, and people are on the road to summer fun. But there's trouble brewing at a small diner on the road to the Outer Banks of North Carolina. Someone is stealing tips! Match your sleuthing skills against waitress Tawny. All the clues are here for you to figure it out. The solution is posted in the comments.  

         “Ya’ll travel safely,” Tawny said, placing the check on the table.  Early June vacationers had been traveling through at a steady stream, heading for the outer banks of North Carolina for their summer beach vacations.  But despite the high turnover at her tables, tips had been disappointingly low.  She’d held off getting new brakes for her car, hoping she’d make enough extra money early in the summer in order to afford them.  At this rate, they’d have to wait another week.  Or two.      

          Loaded down with five plates piled high with pulled pork barbecue sandwiches, fries, coleslaw and fresh from the deep-fryer hushpuppies, she passed the table that had just left and spotted a stack of singles tucked under the salt shaker.  Good.  Maybe her luck was about to change.