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	$210.58	4.536%	$220.1319	$220.13	$220.15	$220.10
Purchase #2	$127.98	5.579%	$135.12	$135.12	$135.10	$135.10
Purchase #3	$130.88	10.246%	$144.29	$144.29	$144.30	$144.30
Purchase #4	$217.94	13.436%	$247.2224	$247.22	$247.20	$247.20
Purchase #5	$96.47	7.294%	$103.5065	$103.51	$103.50	$103.50
Purchase #6	$110.33	5.559%	$116.4632	$116.46	$116.45	$116.50
Purchase #7	$130.65	10.659%	$144.576	$144.58	$144.60	$144.60
7 purchase totals =	$1,024.83		$1,111.3100	$1,111.31	$1,111.30	$1,111.30