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	$164.90	5.462%	$173.9068	$173.91	$173.90	$173.90
Purchase #2	$186.51	12.802%	$210.387	$210.39	$210.40	$210.40
Purchase #3	$36.29	3.607%	$37.599	$37.60	$37.60	$37.60
Purchase #4	$203.75	13.140%	$230.5228	$230.52	$230.50	$230.50
Purchase #5	$86.77	6.380%	$92.3059	$92.31	$92.30	$92.30
Purchase #6	$215.50	10.433%	$237.9831	$237.98	$238.00	$238.00
Purchase #7	$205.52	5.842%	$217.5265	$217.53	$217.55	$217.50
7 purchase totals =	$1,099.24		$1,200.2311	$1,200.24	$1,200.25	$1,200.20