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	$188.76	4.342%	$196.956	$196.96	$196.95	$197.00
Purchase #2	$9.74	10.657%	$10.778	$10.78	$10.80	$10.80
Purchase #3	$125.40	5.590%	$132.4099	$132.41	$132.40	$132.40
Purchase #4	$183.60	5.678%	$194.0248	$194.02	$194.00	$194.00
Purchase #5	$98.77	11.166%	$109.7987	$109.80	$109.80	$109.80
Purchase #6	$50.77	3.690%	$52.6434	$52.64	$52.65	$52.60
Purchase #7	$74.85	4.566%	$78.2677	$78.27	$78.25	$78.30
7 purchase totals =	$731.89		$774.8785	$774.88	$774.85	$774.90