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	$149.60	10.624%	$165.4935	$165.49	$165.50	$165.50
Purchase #2	$12.54	6.170%	$13.3137	$13.31	$13.30	$13.30
Purchase #3	$67.36	3.414%	$69.6597	$69.66	$69.65	$69.70
Purchase #4	$17.89	12.826%	$20.1846	$20.18	$20.20	$20.20
Purchase #5	$175.37	7.608%	$188.7121	$188.71	$188.70	$188.70
Purchase #6	$238.58	7.107%	$255.5359	$255.54	$255.55	$255.50
Purchase #7	$42.52	11.617%	$47.4595	$47.46	$47.45	$47.50
7 purchase totals =	$703.86		$760.3590	$760.35	$760.35	$760.40