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 $58.73   5.479%   $61.9478   $61.95   $61.95   $61.90  
  Purchase #2 $198.82   5.314%   $209.3853   $209.39   $209.40   $209.40  
  Purchase #3 $245.78   10.316%   $271.1347   $271.13   $271.15   $271.10  
  Purchase #4 $59.93   7.847%   $64.6327   $64.63   $64.65   $64.60  
  Purchase #5 $117.60   4.239%   $122.5851   $122.59   $122.60   $122.60  
  Purchase #6 $34.68   9.257%   $37.8903   $37.89   $37.90   $37.90  
  Purchase #7 $244.29   9.562%   $267.649   $267.65   $267.65   $267.60  
  7 purchase totals = $959.83       $1,035.2249   $1,035.23   $1,035.30   $1,035.10