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	$13.93	4.229%	$14.5191	$14.52	$14.50	$14.50
Purchase #2	$225.57	5.488%	$237.9493	$237.95	$237.95	$237.90
Purchase #3	$80.29	8.238%	$86.9043	$86.90	$86.90	$86.90
Purchase #4	$99.32	13.600%	$112.8275	$112.83	$112.85	$112.80
Purchase #5	$70.49	4.348%	$73.5549	$73.55	$73.55	$73.60
Purchase #6	$115.54	7.218%	$123.8797	$123.88	$123.90	$123.90
Purchase #7	$42.71	7.660%	$45.9816	$45.98	$46.00	$46.00
7 purchase totals =	$647.85		$695.6164	$695.61	$695.65	$695.60