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	$132.38	9.462%	$144.9058	$144.91	$144.90	$144.90
Purchase #2	$133.93	9.127%	$146.1538	$146.15	$146.15	$146.20
Purchase #3	$129.59	3.174%	$133.7032	$133.70	$133.70	$133.70
Purchase #4	$167.61	11.845%	$187.4634	$187.46	$187.45	$187.50
Purchase #5	$65.39	10.198%	$72.0585	$72.06	$72.05	$72.10
Purchase #6	$135.43	4.389%	$141.374	$141.37	$141.35	$141.40
Purchase #7	$215.26	10.246%	$237.3155	$237.32	$237.30	$237.30
7 purchase totals =	$979.59		$1,062.9742	$1,062.97	$1,062.90	$1,063.10