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 $195.77   3.535%   $202.6905   $202.69   $202.70   $202.70  
  Purchase #2 $187.57   5.348%   $197.6012   $197.60   $197.60   $197.60  
  Purchase #3 $217.34   3.401%   $224.7317   $224.73   $224.75   $224.70  
  Purchase #4 $237.61   9.769%   $260.8221   $260.82   $260.80   $260.80  
  Purchase #5 $187.39   11.593%   $209.1141   $209.11   $209.10   $209.10  
  Purchase #6 $159.28   12.645%   $179.421   $179.42   $179.40   $179.40  
  Purchase #7 $69.26   3.432%   $71.637   $71.64   $71.65   $71.60  
  7 purchase totals = $1,254.22       $1,346.0176   $1,346.01   $1,346.00   $1,345.90