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	$196.64	4.621%	$205.7267	$205.73	$205.75	$205.70
Purchase #2	$169.40	9.284%	$185.1271	$185.13	$185.15	$185.10
Purchase #3	$231.83	5.561%	$244.7221	$244.72	$244.70	$244.70
Purchase #4	$30.47	9.674%	$33.4177	$33.42	$33.40	$33.40
Purchase #5	$92.66	8.207%	$100.2646	$100.26	$100.25	$100.30
Purchase #6	$185.36	10.130%	$204.137	$204.14	$204.15	$204.10
Purchase #7	$52.66	9.439%	$57.6306	$57.63	$57.65	$57.60
7 purchase totals =	$959.02		$1,031.0258	$1,031.03	$1,031.05	$1,030.90