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 $207.61   3.414%   $214.6978   $214.70   $214.70   $214.70  
  Purchase #2 $212.40   6.603%   $226.4248   $226.42   $226.40   $226.40  
  Purchase #3 $82.66   13.131%   $93.5141   $93.51   $93.50   $93.50  
  Purchase #4 $81.71   11.239%   $90.8934   $90.89   $90.90   $90.90  
  Purchase #5 $78.84   8.431%   $85.487   $85.49   $85.50   $85.50  
  Purchase #6 $189.81   13.162%   $214.7928   $214.79   $214.80   $214.80  
  Purchase #7 $96.71   11.150%   $107.4932   $107.49   $107.50   $107.50  
  7 purchase totals = $949.74       $1,033.3031   $1,033.29   $1,033.30   $1,033.30