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	$124.71	5.793%	$131.9345	$131.93	$131.95	$131.90
Purchase #2	$141.93	3.128%	$146.3696	$146.37	$146.35	$146.40
Purchase #3	$195.87	4.674%	$205.025	$205.03	$205.05	$205.00
Purchase #4	$111.48	8.159%	$120.5757	$120.58	$120.60	$120.60
Purchase #5	$101.94	3.272%	$105.2755	$105.28	$105.30	$105.30
Purchase #6	$127.74	3.541%	$132.2633	$132.26	$132.25	$132.30
Purchase #7	$138.70	9.404%	$151.7433	$151.74	$151.75	$151.70
7 purchase totals =	$942.37		$993.1869	$993.19	$993.25	$993.20