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	$114.50	7.453%	$123.0337	$123.03	$123.05	$123.00
Purchase #2	$58.51	10.517%	$64.6635	$64.66	$64.65	$64.70
Purchase #3	$219.30	9.145%	$239.355	$239.36	$239.35	$239.40
Purchase #4	$145.33	9.335%	$158.8966	$158.90	$158.90	$158.90
Purchase #5	$50.69	11.788%	$56.6653	$56.67	$56.65	$56.70
Purchase #6	$118.62	7.287%	$127.2638	$127.26	$127.25	$127.30
Purchase #7	$249.52	10.262%	$275.1257	$275.13	$275.15	$275.10
7 purchase totals =	$956.47		$1,045.0036	$1,045.01	$1,045.00	$1,045.10