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	$169.89	5.702%	$179.5771	$179.58	$179.60	$179.60
Purchase #2	$118.62	8.710%	$128.9518	$128.95	$128.95	$129.00
Purchase #3	$112.63	13.193%	$127.4893	$127.49	$127.50	$127.50
Purchase #4	$135.77	10.548%	$150.091	$150.09	$150.10	$150.10
Purchase #5	$175.52	11.837%	$196.2963	$196.30	$196.30	$196.30
Purchase #6	$100.50	9.647%	$110.1952	$110.20	$110.20	$110.20
Purchase #7	$148.43	6.693%	$158.3644	$158.36	$158.35	$158.40
7 purchase totals =	$961.36		$1,050.9651	$1,050.97	$1,051.00	$1,051.10