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	$233.95	5.345%	$246.4546	$246.45	$246.45	$246.50
Purchase #2	$173.42	13.258%	$196.412	$196.41	$196.40	$196.40
Purchase #3	$64.63	4.516%	$67.5487	$67.55	$67.55	$67.50
Purchase #4	$52.91	7.714%	$56.9915	$56.99	$57.00	$57.00
Purchase #5	$206.72	7.347%	$221.9077	$221.91	$221.90	$221.90
Purchase #6	$12.90	9.786%	$14.1624	$14.16	$14.15	$14.20
Purchase #7	$231.41	11.631%	$258.3253	$258.33	$258.35	$258.30
7 purchase totals =	$975.94		$1,061.8022	$1,061.80	$1,061.80	$1,061.80