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 $59.68   5.503%   $62.9642   $62.96   $62.95   $63.00  
  Purchase #2 $49.77   10.222%   $54.8575   $54.86   $54.85   $54.90  
  Purchase #3 $224.58   5.408%   $236.7253   $236.73   $236.75   $236.70  
  Purchase #4 $208.39   12.813%   $235.091   $235.09   $235.10   $235.10  
  Purchase #5 $226.65   10.593%   $250.659   $250.66   $250.65   $250.70  
  Purchase #6 $102.96   9.732%   $112.9801   $112.98   $113.00   $113.00  
  Purchase #7 $162.74   10.171%   $179.2923   $179.29   $179.30   $179.30  
  7 purchase totals = $1,034.77       $1,132.5694   $1,132.57   $1,132.60   $1,132.70