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	$135.64	11.828%	$151.6835	$151.68	$151.70	$151.70
Purchase #2	$232.39	13.345%	$263.4024	$263.40	$263.40	$263.40
Purchase #3	$163.51	3.136%	$168.6377	$168.64	$168.65	$168.60
Purchase #4	$100.40	11.602%	$112.0484	$112.05	$112.05	$112.00
Purchase #5	$238.46	7.694%	$256.8071	$256.81	$256.80	$256.80
Purchase #6	$184.57	8.608%	$200.4578	$200.46	$200.45	$200.50
Purchase #7	$56.74	8.130%	$61.353	$61.35	$61.35	$61.40
7 purchase totals =	$1,111.71		$1,214.3899	$1,214.39	$1,214.40	$1,214.40