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 $88.65   7.736%   $95.508   $95.51   $95.50   $95.50  
  Purchase #2 $97.65   10.853%   $108.248   $108.25   $108.25   $108.20  
  Purchase #3 $44.79   8.123%   $48.4283   $48.43   $48.45   $48.40  
  Purchase #4 $42.46   10.353%   $46.8559   $46.86   $46.85   $46.90  
  Purchase #5 $192.63   5.624%   $203.4635   $203.46   $203.45   $203.50  
  Purchase #6 $5.74   8.123%   $6.2063   $6.21   $6.20   $6.20  
  Purchase #7 $193.82   11.408%   $215.931   $215.93   $215.95   $215.90  
  7 purchase totals = $665.74       $724.6410   $724.65   $724.65   $724.60