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 $59.34   5.444%   $62.5705   $62.57   $62.55   $62.60  
  Purchase #2 $239.97   11.414%   $267.3602   $267.36   $267.35   $267.40  
  Purchase #3 $112.75   6.643%   $120.24   $120.24   $120.25   $120.20  
  Purchase #4 $234.37   4.589%   $245.1252   $245.13   $245.15   $245.10  
  Purchase #5 $242.25   7.554%   $260.5496   $260.55   $260.55   $260.50  
  Purchase #6 $113.33   13.494%   $128.6228   $128.62   $128.60   $128.60  
  Purchase #7 $116.41   5.314%   $122.596   $122.60   $122.60   $122.60  
  7 purchase totals = $1,118.42       $1,207.0643   $1,207.07   $1,207.05   $1,207.00