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	$150.37	5.367%	$158.4404	$158.44	$158.45	$158.40
Purchase #2	$17.29	13.835%	$19.6821	$19.68	$19.70	$19.70
Purchase #3	$94.28	6.682%	$100.5798	$100.58	$100.60	$100.60
Purchase #4	$139.39	9.380%	$152.4648	$152.46	$152.45	$152.50
Purchase #5	$91.53	5.433%	$96.5028	$96.50	$96.50	$96.50
Purchase #6	$237.46	7.696%	$255.7349	$255.73	$255.75	$255.70
Purchase #7	$213.30	9.654%	$233.892	$233.89	$233.90	$233.90
7 purchase totals =	$943.62		$1,017.2968	$1,017.28	$1,017.35	$1,017.30