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	$110.27	3.761%	$114.4173	$114.42	$114.40	$114.40
Purchase #2	$151.50	7.287%	$162.5398	$162.54	$162.55	$162.50
Purchase #3	$128.33	11.783%	$143.4511	$143.45	$143.45	$143.50
Purchase #4	$134.95	11.174%	$150.0293	$150.03	$150.05	$150.00
Purchase #5	$227.57	9.711%	$249.6693	$249.67	$249.65	$249.70
Purchase #6	$66.88	8.147%	$72.3287	$72.33	$72.35	$72.30
Purchase #7	$111.69	11.701%	$124.7588	$124.76	$124.75	$124.80
7 purchase totals =	$931.19		$1,017.1943	$1,017.20	$1,017.20	$1,017.20