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	$158.55	8.701%	$172.3454	$172.35	$172.35	$172.30
Purchase #2	$241.93	8.577%	$262.6803	$262.68	$262.70	$262.70
Purchase #3	$67.46	13.411%	$76.5071	$76.51	$76.50	$76.50
Purchase #4	$126.68	12.274%	$142.2287	$142.23	$142.25	$142.20
Purchase #5	$96.95	8.597%	$105.2848	$105.28	$105.30	$105.30
Purchase #6	$153.55	3.427%	$158.8122	$158.81	$158.80	$158.80
Purchase #7	$214.77	9.284%	$234.7092	$234.71	$234.70	$234.70
7 purchase totals =	$1,059.89		$1,152.5677	$1,152.57	$1,152.60	$1,152.50