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	$97.39	12.300%	$109.369	$109.37	$109.35	$109.40
Purchase #2	$120.67	5.462%	$127.261	$127.26	$127.25	$127.30
Purchase #3	$114.93	13.150%	$130.0433	$130.04	$130.05	$130.00
Purchase #4	$11.80	5.652%	$12.4669	$12.47	$12.45	$12.50
Purchase #5	$207.42	13.370%	$235.1521	$235.15	$235.15	$235.20
Purchase #6	$11.58	3.109%	$11.94	$11.94	$11.95	$11.90
Purchase #7	$123.63	3.241%	$127.6368	$127.64	$127.65	$127.60
7 purchase totals =	$687.42		$753.8691	$753.87	$753.85	$753.90