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	$136.74	11.124%	$151.951	$151.95	$151.95	$152.00
Purchase #2	$181.75	13.135%	$205.6229	$205.62	$205.60	$205.60
Purchase #3	$117.39	8.275%	$127.104	$127.10	$127.10	$127.10
Purchase #4	$245.51	5.291%	$258.4999	$258.50	$258.50	$258.50
Purchase #5	$51.39	9.323%	$56.1811	$56.18	$56.20	$56.20
Purchase #6	$90.54	9.855%	$99.4627	$99.46	$99.45	$99.50
Purchase #7	$181.71	4.528%	$189.9378	$189.94	$189.95	$189.90
7 purchase totals =	$1,005.03		$1,088.7594	$1,088.75	$1,088.75	$1,088.80