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	$114.75	5.461%	$121.0165	$121.02	$121.00	$121.00
Purchase #2	$207.81	3.535%	$215.1561	$215.16	$215.15	$215.20
Purchase #3	$143.86	3.844%	$149.39	$149.39	$149.40	$149.40
Purchase #4	$104.89	6.667%	$111.883	$111.88	$111.90	$111.90
Purchase #5	$42.88	7.506%	$46.0986	$46.10	$46.10	$46.10
Purchase #6	$241.47	12.852%	$272.5037	$272.50	$272.50	$272.50
Purchase #7	$158.81	6.461%	$169.0707	$169.07	$169.05	$169.10
7 purchase totals =	$1,014.47		$1,085.1186	$1,085.12	$1,085.10	$1,085.20