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	$230.80	3.228%	$238.2502	$238.25	$238.25	$238.30
Purchase #2	$67.76	7.273%	$72.6882	$72.69	$72.70	$72.70
Purchase #3	$208.28	3.155%	$214.8512	$214.85	$214.85	$214.90
Purchase #4	$13.57	9.473%	$14.8555	$14.86	$14.85	$14.90
Purchase #5	$65.33	13.756%	$74.3168	$74.32	$74.30	$74.30
Purchase #6	$192.90	4.177%	$200.9574	$200.96	$200.95	$201.00
Purchase #7	$180.73	10.750%	$200.1585	$200.16	$200.15	$200.20
7 purchase totals =	$959.37		$1,016.0778	$1,016.09	$1,016.05	$1,016.30