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	$152.37	4.105%	$158.6248	$158.62	$158.60	$158.60
Purchase #2	$152.41	6.636%	$162.5239	$162.52	$162.50	$162.50
Purchase #3	$217.73	10.855%	$241.3646	$241.36	$241.35	$241.40
Purchase #4	$188.55	4.868%	$197.7286	$197.73	$197.75	$197.70
Purchase #5	$100.61	5.698%	$106.3428	$106.34	$106.35	$106.30
Purchase #6	$82.56	3.466%	$85.4215	$85.42	$85.40	$85.40
Purchase #7	$142.39	10.694%	$157.6172	$157.62	$157.60	$157.60
7 purchase totals =	$1,036.62		$1,109.6234	$1,109.61	$1,109.55	$1,109.50