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	$179.84	10.239%	$198.2538	$198.25	$198.25	$198.30
Purchase #2	$165.51	13.736%	$188.2445	$188.24	$188.25	$188.20
Purchase #3	$57.55	8.437%	$62.4055	$62.41	$62.40	$62.40
Purchase #4	$117.66	9.712%	$129.0871	$129.09	$129.10	$129.10
Purchase #5	$92.75	13.800%	$105.5495	$105.55	$105.55	$105.50
Purchase #6	$100.70	10.305%	$111.0771	$111.08	$111.10	$111.10
Purchase #7	$211.56	12.655%	$238.3329	$238.33	$238.35	$238.30
7 purchase totals =	$925.57		$1,032.9504	$1,032.95	$1,033.00	$1,032.90