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	$222.56	8.548%	$241.5844	$241.58	$241.60	$241.60
Purchase #2	$208.71	10.147%	$229.8878	$229.89	$229.90	$229.90
Purchase #3	$244.78	6.313%	$260.233	$260.23	$260.25	$260.20
Purchase #4	$160.67	13.460%	$182.2962	$182.30	$182.30	$182.30
Purchase #5	$19.52	4.548%	$20.4078	$20.41	$20.40	$20.40
Purchase #6	$98.26	6.633%	$104.7776	$104.78	$104.80	$104.80
Purchase #7	$76.96	9.587%	$84.3382	$84.34	$84.35	$84.30
7 purchase totals =	$1,031.46		$1,123.5250	$1,123.53	$1,123.60	$1,123.50