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	$62.61	4.825%	$65.6309	$65.63	$65.65	$65.60
Purchase #2	$112.39	4.452%	$117.3936	$117.39	$117.40	$117.40
Purchase #3	$163.98	9.678%	$179.85	$179.85	$179.85	$179.90
Purchase #4	$158.69	5.447%	$167.3338	$167.33	$167.35	$167.30
Purchase #5	$11.61	6.163%	$12.3255	$12.33	$12.35	$12.30
Purchase #6	$77.84	3.448%	$80.5239	$80.52	$80.50	$80.50
Purchase #7	$64.85	4.723%	$67.9129	$67.91	$67.90	$67.90
7 purchase totals =	$651.97		$690.9706	$690.96	$691.00	$690.90