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	$199.35	11.737%	$222.7477	$222.75	$222.75	$222.70
Purchase #2	$185.89	6.435%	$197.852	$197.85	$197.85	$197.90
Purchase #3	$176.82	4.280%	$184.3879	$184.39	$184.40	$184.40
Purchase #4	$76.67	11.325%	$85.3529	$85.35	$85.35	$85.40
Purchase #5	$100.32	4.302%	$104.6358	$104.64	$104.65	$104.60
Purchase #6	$134.77	5.492%	$142.1716	$142.17	$142.15	$142.20
Purchase #7	$123.25	11.265%	$137.1341	$137.13	$137.15	$137.10
7 purchase totals =	$997.07		$1,074.2820	$1,074.28	$1,074.30	$1,074.30