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	$102.94	7.792%	$110.9611	$110.96	$110.95	$111.00
Purchase #2	$158.91	5.397%	$167.4864	$167.49	$167.50	$167.50
Purchase #3	$189.62	8.680%	$206.079	$206.08	$206.10	$206.10
Purchase #4	$241.83	4.869%	$253.6047	$253.60	$253.60	$253.60
Purchase #5	$159.89	7.755%	$172.2895	$172.29	$172.30	$172.30
Purchase #6	$141.49	3.348%	$146.2271	$146.23	$146.25	$146.20
Purchase #7	$108.91	5.226%	$114.6016	$114.60	$114.60	$114.60
7 purchase totals =	$1,103.59		$1,171.2494	$1,171.25	$1,171.30	$1,171.30