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 $116.80   7.691%   $125.7831   $125.78   $125.80   $125.80  
  Purchase #2 $202.91   4.690%   $212.4265   $212.43   $212.45   $212.40  
  Purchase #3 $201.89   4.699%   $211.3768   $211.38   $211.40   $211.40  
  Purchase #4 $209.88   10.686%   $232.3078   $232.31   $232.30   $232.30  
  Purchase #5 $211.52   6.213%   $224.6617   $224.66   $224.65   $224.70  
  Purchase #6 $116.76   6.706%   $124.5899   $124.59   $124.60   $124.60  
  Purchase #7 $67.31   4.230%   $70.1572   $70.16   $70.15   $70.20  
  7 purchase totals = $1,127.07       $1,201.3030   $1,201.31   $1,201.35   $1,201.40