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	$146.95	9.383%	$160.7383	$160.74	$160.75	$160.70
Purchase #2	$75.79	8.537%	$82.2602	$82.26	$82.25	$82.30
Purchase #3	$130.50	10.537%	$144.2508	$144.25	$144.25	$144.30
Purchase #4	$168.86	4.588%	$176.6073	$176.61	$176.60	$176.60
Purchase #5	$111.33	4.283%	$116.0983	$116.10	$116.10	$116.10
Purchase #6	$87.67	3.391%	$90.6429	$90.64	$90.65	$90.60
Purchase #7	$83.28	13.784%	$94.7593	$94.76	$94.75	$94.80
7 purchase totals =	$804.38		$865.3571	$865.36	$865.35	$865.40