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 $59.81   4.775%   $62.6659   $62.67   $62.65   $62.70  
  Purchase #2 $199.79   7.254%   $214.2828   $214.28   $214.30   $214.30  
  Purchase #3 $143.36   3.499%   $148.3762   $148.38   $148.40   $148.40  
  Purchase #4 $206.37   9.390%   $225.7481   $225.75   $225.75   $225.70  
  Purchase #5 $250.85   7.770%   $270.341   $270.34   $270.35   $270.30  
  Purchase #6 $89.43   13.549%   $101.5469   $101.55   $101.55   $101.50  
  Purchase #7 $97.28   13.716%   $110.6229   $110.62   $110.60   $110.60  
  7 purchase totals = $1,046.89       $1,133.5838   $1,133.59   $1,133.60   $1,133.50