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	$68.84	5.103%	$72.3529	$72.35	$72.35	$72.40
Purchase #2	$225.72	4.385%	$235.6178	$235.62	$235.60	$235.60
Purchase #3	$227.65	7.457%	$244.6259	$244.63	$244.65	$244.60
Purchase #4	$54.71	4.236%	$57.0275	$57.03	$57.05	$57.00
Purchase #5	$156.84	6.659%	$167.284	$167.28	$167.30	$167.30
Purchase #6	$241.44	5.705%	$255.2142	$255.21	$255.20	$255.20
Purchase #7	$138.52	10.645%	$153.2655	$153.27	$153.25	$153.30
7 purchase totals =	$1,113.72		$1,185.3878	$1,185.39	$1,185.40	$1,185.40