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	$162.92	6.761%	$173.935	$173.94	$173.95	$173.90
Purchase #2	$216.28	11.842%	$241.8919	$241.89	$241.90	$241.90
Purchase #3	$162.92	10.308%	$179.7138	$179.71	$179.70	$179.70
Purchase #4	$130.27	6.789%	$139.114	$139.11	$139.10	$139.10
Purchase #5	$154.66	11.680%	$172.7243	$172.72	$172.70	$172.70
Purchase #6	$90.35	4.273%	$94.2107	$94.21	$94.20	$94.20
Purchase #7	$202.39	6.157%	$214.8512	$214.85	$214.85	$214.90
7 purchase totals =	$1,119.79		$1,216.4409	$1,216.43	$1,216.40	$1,216.40