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 $216.46   7.649%   $233.017   $233.02   $233.00   $233.00  
  Purchase #2 $213.53   7.130%   $228.7547   $228.75   $228.75   $228.80  
  Purchase #3 $193.57   12.397%   $217.5669   $217.57   $217.55   $217.60  
  Purchase #4 $112.42   6.427%   $119.6452   $119.65   $119.65   $119.60  
  Purchase #5 $78.56   6.138%   $83.382   $83.38   $83.40   $83.40  
  Purchase #6 $130.41   3.230%   $134.6222   $134.62   $134.60   $134.60  
  Purchase #7 $77.68   12.814%   $87.6339   $87.63   $87.65   $87.60  
  7 purchase totals = $1,022.63       $1,104.6219   $1,104.62   $1,104.60   $1,104.60