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 $92.29   3.657%   $95.665   $95.67   $95.65   $95.70  
  Purchase #2 $214.85   8.258%   $232.5923   $232.59   $232.60   $232.60  
  Purchase #3 $202.71   7.852%   $218.6268   $218.63   $218.65   $218.60  
  Purchase #4 $58.71   11.528%   $65.4781   $65.48   $65.50   $65.50  
  Purchase #5 $215.70   9.198%   $235.5401   $235.54   $235.55   $235.50  
  Purchase #6 $148.73   8.503%   $161.3765   $161.38   $161.40   $161.40  
  Purchase #7 $53.64   7.655%   $57.7461   $57.75   $57.75   $57.70  
  7 purchase totals = $986.63       $1,067.0249   $1,067.04   $1,067.10   $1,067.00