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	$56.73	8.559%	$61.5855	$61.59	$61.60	$61.60
Purchase #2	$93.28	13.825%	$106.176	$106.18	$106.20	$106.20
Purchase #3	$53.33	13.596%	$60.5807	$60.58	$60.60	$60.60
Purchase #4	$127.58	13.283%	$144.5265	$144.53	$144.55	$144.50
Purchase #5	$197.40	8.699%	$214.5718	$214.57	$214.55	$214.60
Purchase #6	$53.78	13.702%	$61.1489	$61.15	$61.15	$61.10
Purchase #7	$141.82	4.109%	$147.6474	$147.65	$147.65	$147.60
7 purchase totals =	$723.92		$796.2368	$796.25	$796.30	$796.20