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	$84.91	12.375%	$95.4176	$95.42	$95.40	$95.40
Purchase #2	$49.38	5.472%	$52.0821	$52.08	$52.10	$52.10
Purchase #3	$52.26	13.418%	$59.2722	$59.27	$59.25	$59.30
Purchase #4	$62.32	7.274%	$66.8532	$66.85	$66.85	$66.90
Purchase #5	$89.47	7.417%	$96.106	$96.11	$96.10	$96.10
Purchase #6	$142.94	10.701%	$158.236	$158.24	$158.25	$158.20
Purchase #7	$180.75	6.816%	$193.0699	$193.07	$193.05	$193.10
7 purchase totals =	$662.03		$721.0370	$721.04	$721.00	$721.10