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	$208.26	5.481%	$219.6747	$219.67	$219.65	$219.70
Purchase #2	$132.69	12.129%	$148.784	$148.78	$148.80	$148.80
Purchase #3	$128.77	12.316%	$144.6293	$144.63	$144.65	$144.60
Purchase #4	$166.78	13.720%	$189.6622	$189.66	$189.65	$189.70
Purchase #5	$178.40	6.608%	$190.1887	$190.19	$190.20	$190.20
Purchase #6	$65.47	6.333%	$69.6162	$69.62	$69.60	$69.60
Purchase #7	$55.69	7.293%	$59.7515	$59.75	$59.75	$59.80
7 purchase totals =	$936.06		$1,022.3066	$1,022.30	$1,022.30	$1,022.40