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	$133.52	11.176%	$148.4422	$148.44	$148.45	$148.40
Purchase #2	$151.75	4.121%	$158.0036	$158.00	$158.00	$158.00
Purchase #3	$62.49	3.387%	$64.6065	$64.61	$64.60	$64.60
Purchase #4	$204.50	8.607%	$222.1013	$222.10	$222.10	$222.10
Purchase #5	$188.27	4.300%	$196.3656	$196.37	$196.35	$196.40
Purchase #6	$227.52	10.619%	$251.6803	$251.68	$251.70	$251.70
Purchase #7	$9.43	12.835%	$10.6403	$10.64	$10.65	$10.60
7 purchase totals =	$977.48		$1,051.8398	$1,051.84	$1,051.85	$1,051.80