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	$109.32	8.108%	$118.1837	$118.18	$118.20	$118.20
Purchase #2	$211.43	5.344%	$222.7288	$222.73	$222.75	$222.70
Purchase #3	$118.46	7.512%	$127.3587	$127.36	$127.35	$127.40
Purchase #4	$42.71	12.640%	$48.1085	$48.11	$48.10	$48.10
Purchase #5	$46.35	12.456%	$52.1234	$52.12	$52.10	$52.10
Purchase #6	$194.96	4.778%	$204.2752	$204.28	$204.30	$204.30
Purchase #7	$245.35	3.401%	$253.6944	$253.69	$253.70	$253.70
7 purchase totals =	$968.58		$1,026.4727	$1,026.47	$1,026.50	$1,026.50