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	$49.61	7.120%	$53.1422	$53.14	$53.15	$53.10
Purchase #2	$129.92	12.335%	$145.9456	$145.95	$145.95	$145.90
Purchase #3	$218.45	12.371%	$245.4744	$245.47	$245.45	$245.50
Purchase #4	$93.82	7.509%	$100.8649	$100.86	$100.85	$100.90
Purchase #5	$216.89	5.654%	$229.153	$229.15	$229.15	$229.20
Purchase #6	$194.26	7.321%	$208.4818	$208.48	$208.50	$208.50
Purchase #7	$46.80	5.453%	$49.352	$49.35	$49.35	$49.40
7 purchase totals =	$949.75		$1,032.4139	$1,032.40	$1,032.40	$1,032.50