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	$130.92	10.466%	$144.6221	$144.62	$144.60	$144.60
Purchase #2	$101.46	4.115%	$105.6351	$105.64	$105.65	$105.60
Purchase #3	$154.45	5.436%	$162.8459	$162.85	$162.85	$162.80
Purchase #4	$247.81	3.205%	$255.7523	$255.75	$255.75	$255.80
Purchase #5	$44.61	3.414%	$46.133	$46.13	$46.15	$46.10
Purchase #6	$227.78	7.304%	$244.4171	$244.42	$244.40	$244.40
Purchase #7	$187.80	11.288%	$208.9989	$209.00	$209.00	$209.00
7 purchase totals =	$1,094.83		$1,168.4044	$1,168.41	$1,168.40	$1,168.30