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	$152.82	11.606%	$170.5563	$170.56	$170.55	$170.60
Purchase #2	$9.36	11.693%	$10.4545	$10.45	$10.45	$10.50
Purchase #3	$182.60	3.654%	$189.2722	$189.27	$189.25	$189.30
Purchase #4	$190.28	10.172%	$209.6353	$209.64	$209.65	$209.60
Purchase #5	$129.52	12.202%	$145.324	$145.32	$145.30	$145.30
Purchase #6	$100.30	11.697%	$112.0321	$112.03	$112.05	$112.00
Purchase #7	$229.40	11.832%	$256.5426	$256.54	$256.55	$256.50
7 purchase totals =	$994.28		$1,093.8170	$1,093.81	$1,093.80	$1,093.80