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	$172.25	13.409%	$195.347	$195.35	$195.35	$195.30
Purchase #2	$193.81	4.347%	$202.2349	$202.23	$202.25	$202.20
Purchase #3	$105.57	6.585%	$112.5218	$112.52	$112.50	$112.50
Purchase #4	$75.38	9.801%	$82.768	$82.77	$82.75	$82.80
Purchase #5	$80.27	11.656%	$89.6263	$89.63	$89.65	$89.60
Purchase #6	$6.34	3.848%	$6.584	$6.58	$6.60	$6.60
Purchase #7	$34.29	3.130%	$35.3633	$35.36	$35.35	$35.40
7 purchase totals =	$667.91		$724.4453	$724.44	$724.45	$724.40