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	$226.50	7.391%	$243.2406	$243.24	$243.25	$243.20
Purchase #2	$224.83	13.679%	$255.5845	$255.58	$255.60	$255.60
Purchase #3	$49.85	10.703%	$55.1854	$55.19	$55.20	$55.20
Purchase #4	$46.47	4.561%	$48.5895	$48.59	$48.60	$48.60
Purchase #5	$221.32	12.337%	$248.6242	$248.62	$248.60	$248.60
Purchase #6	$73.88	7.324%	$79.291	$79.29	$79.30	$79.30
Purchase #7	$83.93	10.126%	$92.4288	$92.43	$92.45	$92.40
7 purchase totals =	$926.78		$1,022.9440	$1,022.94	$1,023.00	$1,022.90