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 $58.95   5.737%   $62.332   $62.33   $62.35   $62.30  
  Purchase #2 $127.52   9.634%   $139.8053   $139.81   $139.80   $139.80  
  Purchase #3 $80.68   8.414%   $87.4684   $87.47   $87.45   $87.50  
  Purchase #4 $204.97   9.725%   $224.9033   $224.90   $224.90   $224.90  
  Purchase #5 $227.28   4.257%   $236.9553   $236.96   $236.95   $237.00  
  Purchase #6 $161.97   13.495%   $183.8279   $183.83   $183.85   $183.80  
  Purchase #7 $146.59   10.598%   $162.1256   $162.13   $162.15   $162.10  
  7 purchase totals = $1,007.96       $1,097.4178   $1,097.43   $1,097.45   $1,097.40