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 $114.36   9.410%   $125.1213   $125.12   $125.10   $125.10  
  Purchase #2 $143.58   3.517%   $148.6297   $148.63   $148.65   $148.60  
  Purchase #3 $27.48   5.534%   $29.0007   $29.00   $29.00   $29.00  
  Purchase #4 $71.80   3.812%   $74.537   $74.54   $74.55   $74.50  
  Purchase #5 $134.36   3.269%   $138.7522   $138.75   $138.75   $138.80  
  Purchase #6 $96.45   9.365%   $105.4825   $105.48   $105.50   $105.50  
  Purchase #7 $249.83   9.468%   $273.4839   $273.48   $273.50   $273.50  
  7 purchase totals = $837.86       $895.0073   $895.00   $895.05   $895.00