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 $72.89   4.460%   $76.1409   $76.14   $76.15   $76.10  
  Purchase #2 $91.88   3.404%   $95.0076   $95.01   $95.00   $95.00  
  Purchase #3 $93.59   4.292%   $97.6069   $97.61   $97.60   $97.60  
  Purchase #4 $247.37   7.849%   $266.7861   $266.79   $266.80   $266.80  
  Purchase #5 $106.38   6.178%   $112.9522   $112.95   $112.95   $113.00  
  Purchase #6 $154.75   3.489%   $160.1492   $160.15   $160.15   $160.10  
  Purchase #7 $198.72   5.576%   $209.8006   $209.80   $209.80   $209.80  
  7 purchase totals = $965.58       $1,018.4435   $1,018.45   $1,018.45   $1,018.40