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 $183.51   7.653%   $197.554   $197.55   $197.55   $197.60  
  Purchase #2 $217.47   7.438%   $233.6454   $233.65   $233.65   $233.60  
  Purchase #3 $161.29   11.439%   $179.74   $179.74   $179.75   $179.70  
  Purchase #4 $97.75   13.792%   $111.2317   $111.23   $111.25   $111.20  
  Purchase #5 $46.78   4.300%   $48.7915   $48.79   $48.80   $48.80  
  Purchase #6 $226.28   3.776%   $234.8243   $234.82   $234.80   $234.80  
  Purchase #7 $116.31   3.622%   $120.5227   $120.52   $120.50   $120.50  
  7 purchase totals = $1,049.39       $1,126.3096   $1,126.30   $1,126.30   $1,126.20