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	$22.44	13.250%	$25.4133	$25.41	$25.40	$25.40
Purchase #2	$10.50	3.860%	$10.9053	$10.91	$10.90	$10.90
Purchase #3	$148.46	3.457%	$153.5923	$153.59	$153.60	$153.60
Purchase #4	$162.86	5.845%	$172.3792	$172.38	$172.40	$172.40
Purchase #5	$62.61	6.776%	$66.8525	$66.85	$66.85	$66.90
Purchase #6	$98.80	12.833%	$111.479	$111.48	$111.50	$111.50
Purchase #7	$162.25	6.606%	$172.9682	$172.97	$172.95	$173.00
7 purchase totals =	$667.92		$713.5898	$713.59	$713.60	$713.70