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	$110.28	11.584%	$123.0548	$123.05	$123.05	$123.10
Purchase #2	$144.97	4.575%	$151.6024	$151.60	$151.60	$151.60
Purchase #3	$89.35	6.846%	$95.4669	$95.47	$95.45	$95.50
Purchase #4	$64.89	12.359%	$72.9098	$72.91	$72.90	$72.90
Purchase #5	$88.32	12.216%	$99.1092	$99.11	$99.10	$99.10
Purchase #6	$239.60	7.494%	$257.5556	$257.56	$257.55	$257.60
Purchase #7	$197.85	8.256%	$214.1845	$214.18	$214.20	$214.20
7 purchase totals =	$935.26		$1,013.8832	$1,013.88	$1,013.85	$1,014.00