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	$181.82	7.380%	$195.2383	$195.24	$195.25	$195.20
Purchase #2	$181.59	7.157%	$194.5864	$194.59	$194.60	$194.60
Purchase #3	$220.43	5.294%	$232.0996	$232.10	$232.10	$232.10
Purchase #4	$78.80	13.784%	$89.6618	$89.66	$89.65	$89.70
Purchase #5	$25.47	6.328%	$27.0817	$27.08	$27.10	$27.10
Purchase #6	$187.53	6.636%	$199.9745	$199.97	$199.95	$200.00
Purchase #7	$158.25	4.423%	$165.2494	$165.25	$165.25	$165.20
7 purchase totals =	$1,033.89		$1,103.8917	$1,103.89	$1,103.90	$1,103.90