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	$131.71	11.180%	$146.4352	$146.44	$146.45	$146.40
Purchase #2	$185.75	13.211%	$210.2894	$210.29	$210.30	$210.30
Purchase #3	$92.85	8.173%	$100.4386	$100.44	$100.45	$100.40
Purchase #4	$88.96	3.442%	$92.022	$92.02	$92.00	$92.00
Purchase #5	$204.69	5.229%	$215.3932	$215.39	$215.40	$215.40
Purchase #6	$58.72	6.797%	$62.7112	$62.71	$62.70	$62.70
Purchase #7	$173.95	13.418%	$197.2906	$197.29	$197.30	$197.30
7 purchase totals =	$936.63		$1,024.5802	$1,024.58	$1,024.60	$1,024.50