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	$181.65	10.625%	$200.9503	$200.95	$200.95	$201.00
Purchase #2	$99.78	10.126%	$109.8837	$109.88	$109.90	$109.90
Purchase #3	$141.91	3.401%	$146.7364	$146.74	$146.75	$146.70
Purchase #4	$40.72	6.566%	$43.3937	$43.39	$43.40	$43.40
Purchase #5	$121.87	4.874%	$127.8099	$127.81	$127.80	$127.80
Purchase #6	$46.27	3.428%	$47.8561	$47.86	$47.85	$47.90
Purchase #7	$169.82	8.621%	$184.4602	$184.46	$184.45	$184.50
7 purchase totals =	$802.02		$861.0903	$861.09	$861.10	$861.20