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 $69.58   3.340%   $71.904   $71.90   $71.90   $71.90  
  Purchase #2 $241.85   10.435%   $267.087   $267.09   $267.10   $267.10  
  Purchase #3 $133.67   9.691%   $146.624   $146.62   $146.60   $146.60  
  Purchase #4 $94.76   3.315%   $97.9013   $97.90   $97.90   $97.90  
  Purchase #5 $161.54   7.120%   $173.0416   $173.04   $173.05   $173.00  
  Purchase #6 $239.55   12.309%   $269.0362   $269.04   $269.05   $269.00  
  Purchase #7 $122.39   3.668%   $126.8793   $126.88   $126.90   $126.90  
  7 purchase totals = $1,063.34       $1,152.4734   $1,152.47   $1,152.50   $1,152.40