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	$214.59	4.216%	$223.6371	$223.64	$223.65	$223.60
Purchase #2	$202.87	6.111%	$215.2674	$215.27	$215.25	$215.30
Purchase #3	$235.26	5.677%	$248.6157	$248.62	$248.60	$248.60
Purchase #4	$221.83	7.319%	$238.0657	$238.07	$238.05	$238.10
Purchase #5	$106.81	4.611%	$111.735	$111.74	$111.75	$111.70
Purchase #6	$36.37	11.837%	$40.6751	$40.68	$40.70	$40.70
Purchase #7	$44.89	12.214%	$50.3729	$50.37	$50.35	$50.40
7 purchase totals =	$1,062.62		$1,128.3689	$1,128.39	$1,128.35	$1,128.40