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 $119.93   5.480%   $126.5022   $126.50   $126.50   $126.50  
  Purchase #2 $131.33   4.467%   $137.1965   $137.20   $137.20   $137.20  
  Purchase #3 $152.43   6.414%   $162.2069   $162.21   $162.20   $162.20  
  Purchase #4 $107.37   8.641%   $116.6478   $116.65   $116.65   $116.60  
  Purchase #5 $227.79   6.413%   $242.3982   $242.40   $242.40   $242.40  
  Purchase #6 $218.87   6.663%   $233.4533   $233.45   $233.45   $233.50  
  Purchase #7 $46.86   7.123%   $50.1978   $50.20   $50.20   $50.20  
  7 purchase totals = $1,004.58       $1,068.6027   $1,068.61   $1,068.60   $1,068.60