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	$173.25	13.184%	$196.0913	$196.09	$196.10	$196.10
Purchase #2	$81.80	6.326%	$86.9747	$86.97	$86.95	$87.00
Purchase #3	$42.43	13.410%	$48.1199	$48.12	$48.10	$48.10
Purchase #4	$175.52	9.616%	$192.398	$192.40	$192.40	$192.40
Purchase #5	$185.47	5.868%	$196.3534	$196.35	$196.35	$196.40
Purchase #6	$9.79	3.810%	$10.163	$10.16	$10.15	$10.20
Purchase #7	$20.92	4.240%	$21.807	$21.81	$21.80	$21.80
7 purchase totals =	$689.18		$751.9073	$751.90	$751.85	$752.00