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 $58.53   6.286%   $62.2092   $62.21   $62.20   $62.20  
  Purchase #2 $242.84   4.651%   $254.1345   $254.13   $254.15   $254.10  
  Purchase #3 $59.28   8.245%   $64.1676   $64.17   $64.15   $64.20  
  Purchase #4 $117.56   4.583%   $122.9478   $122.95   $122.95   $122.90  
  Purchase #5 $157.59   3.134%   $162.5289   $162.53   $162.55   $162.50  
  Purchase #6 $185.59   6.715%   $198.0524   $198.05   $198.05   $198.10  
  Purchase #7 $220.89   5.343%   $232.6922   $232.69   $232.70   $232.70  
  7 purchase totals = $1,042.28       $1,096.7326   $1,096.73   $1,096.75   $1,096.70