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	$49.66	4.737%	$52.0124	$52.01	$52.00	$52.00
Purchase #2	$46.79	9.543%	$51.2552	$51.26	$51.25	$51.30
Purchase #3	$12.59	13.707%	$14.3157	$14.32	$14.30	$14.30
Purchase #4	$120.81	6.725%	$128.9345	$128.93	$128.95	$128.90
Purchase #5	$131.88	9.222%	$144.042	$144.04	$144.05	$144.00
Purchase #6	$156.86	5.259%	$165.1093	$165.11	$165.10	$165.10
Purchase #7	$143.86	5.260%	$151.427	$151.43	$151.45	$151.40
7 purchase totals =	$662.45		$707.0961	$707.10	$707.10	$707.00