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 $57.46   9.582%   $62.9658   $62.97   $62.95   $63.00  
  Purchase #2 $193.81   7.161%   $207.6887   $207.69   $207.70   $207.70  
  Purchase #3 $174.40   9.115%   $190.2966   $190.30   $190.30   $190.30  
  Purchase #4 $150.55   9.504%   $164.8583   $164.86   $164.85   $164.90  
  Purchase #5 $23.95   13.470%   $27.1761   $27.18   $27.20   $27.20  
  Purchase #6 $200.44   7.769%   $216.0122   $216.01   $216.00   $216.00  
  Purchase #7 $161.70   9.696%   $177.3784   $177.38   $177.40   $177.40  
  7 purchase totals = $962.31       $1,046.3761   $1,046.39   $1,046.40   $1,046.50