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	$179.40	9.355%	$196.1829	$196.18	$196.20	$196.20
Purchase #2	$247.77	4.384%	$258.6322	$258.63	$258.65	$258.60
Purchase #3	$44.90	3.350%	$46.4042	$46.40	$46.40	$46.40
Purchase #4	$153.46	3.293%	$158.5134	$158.51	$158.50	$158.50
Purchase #5	$154.47	8.640%	$167.8162	$167.82	$167.80	$167.80
Purchase #6	$192.50	13.836%	$219.1343	$219.13	$219.15	$219.10
Purchase #7	$174.41	9.376%	$190.7627	$190.76	$190.75	$190.80
7 purchase totals =	$1,146.91		$1,237.4459	$1,237.43	$1,237.45	$1,237.40