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 $108.95   5.170%   $114.5827   $114.58   $114.60   $114.60  
  Purchase #2 $213.94   13.444%   $242.7021   $242.70   $242.70   $242.70  
  Purchase #3 $39.38   9.652%   $43.181   $43.18   $43.20   $43.20  
  Purchase #4 $201.38   11.494%   $224.5266   $224.53   $224.55   $224.50  
  Purchase #5 $234.36   5.395%   $247.0037   $247.00   $247.00   $247.00  
  Purchase #6 $156.98   3.458%   $162.4084   $162.41   $162.40   $162.40  
  Purchase #7 $88.42   12.632%   $99.5892   $99.59   $99.60   $99.60  
  7 purchase totals = $1,043.41       $1,133.9937   $1,133.99   $1,134.05   $1,134.00