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	$222.40	3.277%	$229.688	$229.69	$229.70	$229.70
Purchase #2	$75.53	10.705%	$83.6155	$83.62	$83.60	$83.60
Purchase #3	$66.65	7.384%	$71.5714	$71.57	$71.55	$71.60
Purchase #4	$52.35	9.726%	$57.4416	$57.44	$57.45	$57.40
Purchase #5	$205.77	3.239%	$212.4349	$212.43	$212.45	$212.40
Purchase #6	$187.87	4.349%	$196.0405	$196.04	$196.05	$196.00
Purchase #7	$12.32	13.493%	$13.9823	$13.98	$14.00	$14.00
7 purchase totals =	$822.89		$864.7742	$864.77	$864.80	$864.70