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 $92.42   13.180%   $104.601   $104.60   $104.60   $104.60  
  Purchase #2 $213.52   11.420%   $237.904   $237.90   $237.90   $237.90  
  Purchase #3 $13.61   3.754%   $14.1209   $14.12   $14.10   $14.10  
  Purchase #4 $217.69   11.874%   $243.5385   $243.54   $243.55   $243.50  
  Purchase #5 $217.89   7.821%   $234.9312   $234.93   $234.95   $234.90  
  Purchase #6 $19.86   11.745%   $22.1926   $22.19   $22.20   $22.20  
  Purchase #7 $238.31   6.314%   $253.3569   $253.36   $253.35   $253.40  
  7 purchase totals = $1,013.30       $1,110.6451   $1,110.64   $1,110.65   $1,110.60