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	$155.60	7.218%	$166.8312	$166.83	$166.85	$166.80
Purchase #2	$122.68	6.375%	$130.5009	$130.50	$130.50	$130.50
Purchase #3	$196.91	4.253%	$205.2846	$205.28	$205.30	$205.30
Purchase #4	$137.96	3.136%	$142.2864	$142.29	$142.30	$142.30
Purchase #5	$55.29	13.559%	$62.7868	$62.79	$62.80	$62.80
Purchase #6	$172.86	11.196%	$192.2134	$192.21	$192.20	$192.20
Purchase #7	$111.59	6.750%	$119.1223	$119.12	$119.10	$119.10
7 purchase totals =	$952.89		$1,019.0256	$1,019.02	$1,019.05	$1,019.00