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	$168.36	3.268%	$173.862	$173.86	$173.85	$173.90
Purchase #2	$120.97	3.720%	$125.4701	$125.47	$125.45	$125.50
Purchase #3	$210.45	13.773%	$239.4353	$239.44	$239.45	$239.40
Purchase #4	$234.48	8.339%	$254.0333	$254.03	$254.05	$254.00
Purchase #5	$75.42	4.587%	$78.8795	$78.88	$78.90	$78.90
Purchase #6	$223.27	4.526%	$233.3752	$233.38	$233.40	$233.40
Purchase #7	$50.71	13.107%	$57.3566	$57.36	$57.35	$57.40
7 purchase totals =	$1,083.66		$1,162.4120	$1,162.42	$1,162.45	$1,162.50