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	$162.28	10.287%	$178.9737	$178.97	$178.95	$179.00
Purchase #2	$194.55	11.427%	$216.7812	$216.78	$216.80	$216.80
Purchase #3	$20.40	11.222%	$22.6893	$22.69	$22.70	$22.70
Purchase #4	$157.91	11.204%	$175.6022	$175.60	$175.60	$175.60
Purchase #5	$47.81	13.471%	$54.2505	$54.25	$54.25	$54.30
Purchase #6	$176.51	7.559%	$189.8524	$189.85	$189.85	$189.90
Purchase #7	$117.59	8.140%	$127.1618	$127.16	$127.15	$127.20
7 purchase totals =	$877.05		$965.3111	$965.30	$965.30	$965.50