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	$56.81	9.317%	$62.103	$62.10	$62.10	$62.10
Purchase #2	$57.28	8.756%	$62.2954	$62.30	$62.30	$62.30
Purchase #3	$138.59	6.137%	$147.0953	$147.10	$147.10	$147.10
Purchase #4	$226.48	12.783%	$255.4309	$255.43	$255.45	$255.40
Purchase #5	$127.82	8.459%	$138.6323	$138.63	$138.65	$138.60
Purchase #6	$176.85	7.217%	$189.6133	$189.61	$189.60	$189.60
Purchase #7	$227.46	12.174%	$255.151	$255.15	$255.15	$255.20
7 purchase totals =	$1,011.29		$1,110.3212	$1,110.32	$1,110.35	$1,110.30