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	$174.50	6.369%	$185.6139	$185.61	$185.60	$185.60
Purchase #2	$235.65	8.316%	$255.2467	$255.25	$255.25	$255.20
Purchase #3	$74.46	3.373%	$76.9715	$76.97	$76.95	$77.00
Purchase #4	$219.85	7.228%	$235.7408	$235.74	$235.75	$235.70
Purchase #5	$73.44	6.348%	$78.102	$78.10	$78.10	$78.10
Purchase #6	$64.45	3.198%	$66.5111	$66.51	$66.50	$66.50
Purchase #7	$61.38	7.770%	$66.1492	$66.15	$66.15	$66.10
7 purchase totals =	$903.73		$964.3352	$964.33	$964.30	$964.20