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 $58.54   7.541%   $62.9545   $62.95   $62.95   $63.00  
  Purchase #2 $167.84   6.780%   $179.2196   $179.22   $179.20   $179.20  
  Purchase #3 $105.89   7.551%   $113.8858   $113.89   $113.90   $113.90  
  Purchase #4 $169.98   4.715%   $177.9946   $177.99   $178.00   $178.00  
  Purchase #5 $112.46   3.668%   $116.585   $116.59   $116.60   $116.60  
  Purchase #6 $148.88   11.533%   $166.0503   $166.05   $166.05   $166.10  
  Purchase #7 $236.27   4.357%   $246.5643   $246.56   $246.55   $246.60  
  7 purchase totals = $999.86       $1,063.2541   $1,063.25   $1,063.25   $1,063.40