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	$239.58	9.641%	$262.6779	$262.68	$262.70	$262.70
Purchase #2	$116.33	9.230%	$127.0673	$127.07	$127.05	$127.10
Purchase #3	$248.48	10.623%	$274.876	$274.88	$274.90	$274.90
Purchase #4	$7.33	5.680%	$7.7463	$7.75	$7.75	$7.70
Purchase #5	$99.35	10.419%	$109.7013	$109.70	$109.70	$109.70
Purchase #6	$84.86	10.395%	$93.6812	$93.68	$93.70	$93.70
Purchase #7	$221.82	5.342%	$233.6696	$233.67	$233.65	$233.70
7 purchase totals =	$1,017.75		$1,109.4196	$1,109.43	$1,109.45	$1,109.50