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	$67.76	5.778%	$71.6752	$71.68	$71.70	$71.70
Purchase #2	$92.67	3.219%	$95.653	$95.65	$95.65	$95.70
Purchase #3	$35.87	6.820%	$38.3163	$38.32	$38.30	$38.30
Purchase #4	$107.73	3.481%	$111.4801	$111.48	$111.50	$111.50
Purchase #5	$139.86	7.286%	$150.0502	$150.05	$150.05	$150.10
Purchase #6	$27.97	10.174%	$30.8157	$30.82	$30.80	$30.80
Purchase #7	$187.75	11.113%	$208.6147	$208.61	$208.60	$208.60
7 purchase totals =	$659.61		$706.6052	$706.61	$706.60	$706.70