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	$162.76	8.103%	$175.9484	$175.95	$175.95	$175.90
Purchase #2	$99.58	7.118%	$106.6681	$106.67	$106.65	$106.70
Purchase #3	$71.54	9.191%	$78.1152	$78.12	$78.10	$78.10
Purchase #4	$112.35	13.765%	$127.815	$127.82	$127.80	$127.80
Purchase #5	$38.29	10.382%	$42.2653	$42.27	$42.25	$42.30
Purchase #6	$12.74	11.749%	$14.2368	$14.24	$14.25	$14.20
Purchase #7	$236.85	8.544%	$257.0865	$257.09	$257.10	$257.10
7 purchase totals =	$734.11		$802.1353	$802.16	$802.10	$802.10