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	$183.86	4.477%	$192.0914	$192.09	$192.10	$192.10
Purchase #2	$9.62	11.277%	$10.7048	$10.70	$10.70	$10.70
Purchase #3	$31.74	10.786%	$35.1635	$35.16	$35.15	$35.20
Purchase #4	$39.59	5.760%	$41.8704	$41.87	$41.85	$41.90
Purchase #5	$219.56	11.485%	$244.7765	$244.78	$244.80	$244.80
Purchase #6	$42.60	4.438%	$44.4906	$44.49	$44.50	$44.50
Purchase #7	$159.59	7.863%	$172.1386	$172.14	$172.15	$172.10
7 purchase totals =	$686.56		$741.2358	$741.23	$741.25	$741.30