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	$215.36	8.643%	$233.9736	$233.97	$233.95	$234.00
Purchase #2	$141.54	13.328%	$160.4045	$160.40	$160.40	$160.40
Purchase #3	$59.40	12.326%	$66.7216	$66.72	$66.70	$66.70
Purchase #4	$148.52	6.481%	$158.1456	$158.15	$158.15	$158.10
Purchase #5	$82.93	4.788%	$86.9007	$86.90	$86.90	$86.90
Purchase #6	$234.62	4.247%	$244.5843	$244.58	$244.60	$244.60
Purchase #7	$52.65	9.135%	$57.4596	$57.46	$57.45	$57.50
7 purchase totals =	$935.02		$1,008.1899	$1,008.18	$1,008.15	$1,008.20