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	$137.62	4.243%	$143.4592	$143.46	$143.45	$143.50
Purchase #2	$59.36	6.407%	$63.1632	$63.16	$63.15	$63.20
Purchase #3	$205.60	3.278%	$212.3396	$212.34	$212.35	$212.30
Purchase #4	$169.50	12.162%	$190.1146	$190.11	$190.10	$190.10
Purchase #5	$44.27	3.221%	$45.6959	$45.70	$45.70	$45.70
Purchase #6	$240.58	10.321%	$265.4103	$265.41	$265.40	$265.40
Purchase #7	$150.25	10.258%	$165.6626	$165.66	$165.65	$165.70
7 purchase totals =	$1,007.18		$1,085.8454	$1,085.84	$1,085.80	$1,085.90