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 $59.42   5.217%   $62.5199   $62.52   $62.50   $62.50  
  Purchase #2 $232.84   4.228%   $242.6845   $242.68   $242.70   $242.70  
  Purchase #3 $215.88   9.511%   $236.4123   $236.41   $236.40   $236.40  
  Purchase #4 $185.88   4.779%   $194.7632   $194.76   $194.75   $194.80  
  Purchase #5 $10.66   5.173%   $11.2114   $11.21   $11.20   $11.20  
  Purchase #6 $182.68   11.626%   $203.9184   $203.92   $203.90   $203.90  
  Purchase #7 $56.77   3.111%   $58.5361   $58.54   $58.55   $58.50  
  7 purchase totals = $944.13       $1,010.0458   $1,010.04   $1,010.00   $1,010.00