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	$128.83	3.413%	$133.227	$133.23	$133.25	$133.20
Purchase #2	$112.25	13.118%	$126.975	$126.98	$127.00	$127.00
Purchase #3	$88.91	6.266%	$94.4811	$94.48	$94.50	$94.50
Purchase #4	$247.57	3.173%	$255.4254	$255.43	$255.45	$255.40
Purchase #5	$59.62	13.425%	$67.624	$67.62	$67.60	$67.60
Purchase #6	$19.52	10.836%	$21.6352	$21.64	$21.65	$21.60
Purchase #7	$21.63	10.629%	$23.9291	$23.93	$23.95	$23.90
7 purchase totals =	$678.33		$723.2968	$723.31	$723.40	$723.20