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	$182.92	6.482%	$194.7769	$194.78	$194.80	$194.80
Purchase #2	$11.64	6.467%	$12.3928	$12.39	$12.40	$12.40
Purchase #3	$19.79	5.614%	$20.901	$20.90	$20.90	$20.90
Purchase #4	$241.83	10.399%	$266.9779	$266.98	$267.00	$267.00
Purchase #5	$243.66	7.782%	$262.6216	$262.62	$262.60	$262.60
Purchase #6	$115.35	13.840%	$131.3144	$131.31	$131.30	$131.30
Purchase #7	$126.71	8.569%	$137.5678	$137.57	$137.55	$137.60
7 purchase totals =	$941.90		$1,026.5524	$1,026.55	$1,026.55	$1,026.60