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	$211.87	7.217%	$227.1607	$227.16	$227.15	$227.20
Purchase #2	$112.67	13.584%	$127.9751	$127.98	$128.00	$128.00
Purchase #3	$33.48	13.254%	$37.9174	$37.92	$37.90	$37.90
Purchase #4	$217.55	5.425%	$229.3521	$229.35	$229.35	$229.40
Purchase #5	$73.95	5.836%	$78.2657	$78.27	$78.25	$78.30
Purchase #6	$127.41	3.462%	$131.8209	$131.82	$131.80	$131.80
Purchase #7	$214.54	11.690%	$239.6197	$239.62	$239.60	$239.60
7 purchase totals =	$991.47		$1,072.1116	$1,072.12	$1,072.05	$1,072.20