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	$127.54	12.554%	$143.5514	$143.55	$143.55	$143.60
Purchase #2	$232.99	3.806%	$241.8576	$241.86	$241.85	$241.90
Purchase #3	$237.98	3.683%	$246.7448	$246.74	$246.75	$246.70
Purchase #4	$71.66	9.731%	$78.6332	$78.63	$78.65	$78.60
Purchase #5	$108.35	3.154%	$111.7674	$111.77	$111.75	$111.80
Purchase #6	$125.31	8.231%	$135.6243	$135.62	$135.60	$135.60
Purchase #7	$119.65	3.123%	$123.3867	$123.39	$123.40	$123.40
7 purchase totals =	$1,023.48		$1,081.5654	$1,081.56	$1,081.55	$1,081.60