Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
  Case Tag  
Price  
Sales  
Tax %  
Raw Total  
Incl. Sales Tax  
Rounded  
to Penny  
Rounded  
to Nickel  
Rounded  
to Dime  
  Purchase #1 $57.57   7.625%   $61.9597   $61.96   $61.95   $62.00  
  Purchase #2 $244.96   7.444%   $263.1948   $263.19   $263.20   $263.20  
  Purchase #3 $97.93   12.482%   $110.1536   $110.15   $110.15   $110.20  
  Purchase #4 $41.94   13.516%   $47.6086   $47.61   $47.60   $47.60  
  Purchase #5 $239.78   7.773%   $258.4181   $258.42   $258.40   $258.40  
  Purchase #6 $111.46   7.738%   $120.0848   $120.08   $120.10   $120.10  
  Purchase #7 $197.25   9.734%   $216.4503   $216.45   $216.45   $216.50  
  7 purchase totals = $990.89       $1,077.8699   $1,077.86   $1,077.85   $1,078.00