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	$97.36	3.608%	$100.8727	$100.87	$100.85	$100.90
Purchase #2	$110.77	13.769%	$126.0219	$126.02	$126.00	$126.00
Purchase #3	$115.61	10.274%	$127.4878	$127.49	$127.50	$127.50
Purchase #4	$152.49	5.290%	$160.5567	$160.56	$160.55	$160.60
Purchase #5	$169.72	4.429%	$177.2369	$177.24	$177.25	$177.20
Purchase #6	$141.60	4.839%	$148.452	$148.45	$148.45	$148.50
Purchase #7	$183.29	12.222%	$205.6917	$205.69	$205.70	$205.70
7 purchase totals =	$970.84		$1,046.3197	$1,046.32	$1,046.30	$1,046.40