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	$100.64	8.264%	$108.9569	$108.96	$108.95	$109.00
Purchase #2	$59.45	12.116%	$66.653	$66.65	$66.65	$66.70
Purchase #3	$169.71	8.583%	$184.2762	$184.28	$184.30	$184.30
Purchase #4	$59.33	4.353%	$61.9126	$61.91	$61.90	$61.90
Purchase #5	$189.62	11.760%	$211.9193	$211.92	$211.90	$211.90
Purchase #6	$149.33	4.130%	$155.4973	$155.50	$155.50	$155.50
Purchase #7	$241.91	10.620%	$267.6008	$267.60	$267.60	$267.60
7 purchase totals =	$969.99		$1,056.8161	$1,056.82	$1,056.80	$1,056.90