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 $58.85   5.774%   $62.248   $62.25   $62.25   $62.20  
  Purchase #2 $227.58   11.258%   $253.201   $253.20   $253.20   $253.20  
  Purchase #3 $185.39   10.253%   $204.398   $204.40   $204.40   $204.40  
  Purchase #4 $199.81   11.458%   $222.7042   $222.70   $222.70   $222.70  
  Purchase #5 $164.32   3.739%   $170.4639   $170.46   $170.45   $170.50  
  Purchase #6 $146.43   4.290%   $152.7118   $152.71   $152.70   $152.70  
  Purchase #7 $195.80   3.210%   $202.0852   $202.09   $202.10   $202.10  
  7 purchase totals = $1,178.18       $1,267.8121   $1,267.81   $1,267.80   $1,267.80