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	$218.35	7.727%	$235.2219	$235.22	$235.20	$235.20
Purchase #2	$20.88	4.773%	$21.8766	$21.88	$21.90	$21.90
Purchase #3	$163.65	13.375%	$185.5382	$185.54	$185.55	$185.50
Purchase #4	$155.69	3.360%	$160.9212	$160.92	$160.90	$160.90
Purchase #5	$215.97	10.530%	$238.7116	$238.71	$238.70	$238.70
Purchase #6	$119.92	8.113%	$129.6491	$129.65	$129.65	$129.60
Purchase #7	$107.74	3.812%	$111.847	$111.85	$111.85	$111.80
7 purchase totals =	$1,002.20		$1,083.7656	$1,083.77	$1,083.75	$1,083.60