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	$175.63	11.544%	$195.9047	$195.90	$195.90	$195.90
Purchase #2	$55.58	11.303%	$61.8622	$61.86	$61.85	$61.90
Purchase #3	$203.57	11.428%	$226.834	$226.83	$226.85	$226.80
Purchase #4	$112.27	5.236%	$118.1485	$118.15	$118.15	$118.10
Purchase #5	$33.43	11.301%	$37.2079	$37.21	$37.20	$37.20
Purchase #6	$18.87	3.796%	$19.5863	$19.59	$19.60	$19.60
Purchase #7	$21.71	13.292%	$24.5957	$24.60	$24.60	$24.60
7 purchase totals =	$621.06		$684.1393	$684.14	$684.15	$684.10