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	$197.35	10.847%	$218.7566	$218.76	$218.75	$218.80
Purchase #2	$11.40	5.469%	$12.0235	$12.02	$12.00	$12.00
Purchase #3	$101.94	8.505%	$110.61	$110.61	$110.60	$110.60
Purchase #4	$232.52	6.522%	$247.685	$247.69	$247.70	$247.70
Purchase #5	$118.77	7.421%	$127.5839	$127.58	$127.60	$127.60
Purchase #6	$83.92	8.772%	$91.2815	$91.28	$91.30	$91.30
Purchase #7	$249.99	5.556%	$263.8794	$263.88	$263.90	$263.90
7 purchase totals =	$995.89		$1,071.8199	$1,071.82	$1,071.85	$1,071.90