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	$146.82	4.442%	$153.3417	$153.34	$153.35	$153.30
Purchase #2	$170.85	5.662%	$180.5235	$180.52	$180.50	$180.50
Purchase #3	$107.96	3.130%	$111.3391	$111.34	$111.35	$111.30
Purchase #4	$78.33	11.540%	$87.3693	$87.37	$87.35	$87.40
Purchase #5	$29.28	11.569%	$32.6674	$32.67	$32.65	$32.70
Purchase #6	$44.41	4.227%	$46.2872	$46.29	$46.30	$46.30
Purchase #7	$117.99	4.764%	$123.611	$123.61	$123.60	$123.60
7 purchase totals =	$695.64		$735.1392	$735.14	$735.10	$735.10