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	$200.75	11.737%	$224.312	$224.31	$224.30	$224.30
Purchase #2	$78.25	5.548%	$82.5913	$82.59	$82.60	$82.60
Purchase #3	$177.61	3.689%	$184.162	$184.16	$184.15	$184.20
Purchase #4	$211.46	11.689%	$236.1776	$236.18	$236.20	$236.20
Purchase #5	$86.38	5.182%	$90.8562	$90.86	$90.85	$90.90
Purchase #6	$88.42	12.709%	$99.6573	$99.66	$99.65	$99.70
Purchase #7	$233.47	7.429%	$250.8145	$250.81	$250.80	$250.80
7 purchase totals =	$1,076.34		$1,168.5709	$1,168.57	$1,168.55	$1,168.70