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	$195.95	13.450%	$222.3053	$222.31	$222.30	$222.30
Purchase #2	$172.37	11.713%	$192.5597	$192.56	$192.55	$192.60
Purchase #3	$250.71	10.399%	$276.7813	$276.78	$276.80	$276.80
Purchase #4	$134.36	13.492%	$152.4879	$152.49	$152.50	$152.50
Purchase #5	$57.62	5.282%	$60.6635	$60.66	$60.65	$60.70
Purchase #6	$198.69	6.597%	$211.7976	$211.80	$211.80	$211.80
Purchase #7	$31.40	12.321%	$35.2688	$35.27	$35.25	$35.30
7 purchase totals =	$1,041.10		$1,151.8641	$1,151.87	$1,151.85	$1,152.00