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	$102.92	8.615%	$111.7866	$111.79	$111.80	$111.80
Purchase #2	$66.35	10.317%	$73.1953	$73.20	$73.20	$73.20
Purchase #3	$191.58	11.341%	$213.3071	$213.31	$213.30	$213.30
Purchase #4	$86.48	13.369%	$98.0415	$98.04	$98.05	$98.00
Purchase #5	$151.73	13.392%	$172.0497	$172.05	$172.05	$172.00
Purchase #6	$216.28	6.612%	$230.5804	$230.58	$230.60	$230.60
Purchase #7	$172.85	13.572%	$196.3092	$196.31	$196.30	$196.30
7 purchase totals =	$988.19		$1,095.2698	$1,095.28	$1,095.30	$1,095.20