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 $108.37   5.468%   $114.2957   $114.30   $114.30   $114.30  
  Purchase #2 $247.86   5.475%   $261.4303   $261.43   $261.45   $261.40  
  Purchase #3 $129.99   6.789%   $138.815   $138.82   $138.80   $138.80  
  Purchase #4 $160.43   9.641%   $175.8971   $175.90   $175.90   $175.90  
  Purchase #5 $106.91   9.814%   $117.4021   $117.40   $117.40   $117.40  
  Purchase #6 $212.41   9.627%   $232.8587   $232.86   $232.85   $232.90  
  Purchase #7 $138.43   8.260%   $149.8643   $149.86   $149.85   $149.90  
  7 purchase totals = $1,104.40       $1,190.5632   $1,190.57   $1,190.55   $1,190.60