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	$168.62	3.658%	$174.7881	$174.79	$174.80	$174.80
Purchase #2	$114.92	3.370%	$118.7928	$118.79	$118.80	$118.80
Purchase #3	$217.82	7.368%	$233.869	$233.87	$233.85	$233.90
Purchase #4	$211.79	6.444%	$225.4377	$225.44	$225.45	$225.40
Purchase #5	$151.38	11.612%	$168.9582	$168.96	$168.95	$169.00
Purchase #6	$55.64	7.574%	$59.8542	$59.85	$59.85	$59.90
Purchase #7	$128.86	11.185%	$143.273	$143.27	$143.25	$143.30
7 purchase totals =	$1,049.03		$1,124.9730	$1,124.97	$1,124.95	$1,125.10