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 $69.26   4.385%   $72.2971   $72.30   $72.30   $72.30  
  Purchase #2 $202.66   6.213%   $215.2513   $215.25   $215.25   $215.30  
  Purchase #3 $73.86   3.487%   $76.4355   $76.44   $76.45   $76.40  
  Purchase #4 $128.27   4.645%   $134.2281   $134.23   $134.25   $134.20  
  Purchase #5 $233.53   12.202%   $262.0253   $262.03   $262.05   $262.00  
  Purchase #6 $32.64   4.823%   $34.2142   $34.21   $34.20   $34.20  
  Purchase #7 $191.89   11.510%   $213.9765   $213.98   $214.00   $214.00  
  7 purchase totals = $932.11       $1,008.4280   $1,008.44   $1,008.50   $1,008.40