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	$214.35	6.293%	$227.839	$227.84	$227.85	$227.80
Purchase #2	$69.80	4.109%	$72.6681	$72.67	$72.65	$72.70
Purchase #3	$152.27	11.581%	$169.9044	$169.90	$169.90	$169.90
Purchase #4	$61.98	8.494%	$67.2446	$67.24	$67.25	$67.20
Purchase #5	$121.40	13.791%	$138.1423	$138.14	$138.15	$138.10
Purchase #6	$144.90	5.281%	$152.5522	$152.55	$152.55	$152.60
Purchase #7	$234.57	9.249%	$256.2654	$256.27	$256.25	$256.30
7 purchase totals =	$999.27		$1,084.6160	$1,084.61	$1,084.60	$1,084.60