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 $104.55   9.192%   $114.1602   $114.16   $114.15   $114.20  
  Purchase #2 $247.49   4.652%   $259.0032   $259.00   $259.00   $259.00  
  Purchase #3 $36.79   4.154%   $38.3183   $38.32   $38.30   $38.30  
  Purchase #4 $51.94   12.724%   $58.5488   $58.55   $58.55   $58.50  
  Purchase #5 $247.79   9.244%   $270.6957   $270.70   $270.70   $270.70  
  Purchase #6 $178.30   11.289%   $198.4283   $198.43   $198.45   $198.40  
  Purchase #7 $169.31   10.708%   $187.4397   $187.44   $187.45   $187.40  
  7 purchase totals = $1,036.17       $1,126.5942   $1,126.60   $1,126.60   $1,126.50