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	$186.92	12.185%	$209.6962	$209.70	$209.70	$209.70
Purchase #2	$5.41	3.529%	$5.6009	$5.60	$5.60	$5.60
Purchase #3	$10.86	11.783%	$12.1396	$12.14	$12.15	$12.10
Purchase #4	$231.56	11.601%	$258.4233	$258.42	$258.40	$258.40
Purchase #5	$160.38	7.671%	$172.6827	$172.68	$172.70	$172.70
Purchase #6	$238.46	6.344%	$253.5879	$253.59	$253.60	$253.60
Purchase #7	$94.42	4.731%	$98.887	$98.89	$98.90	$98.90
7 purchase totals =	$928.01		$1,011.0176	$1,011.02	$1,011.05	$1,011.00