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	$196.87	5.765%	$208.2196	$208.22	$208.20	$208.20
Purchase #2	$126.41	10.354%	$139.4985	$139.50	$139.50	$139.50
Purchase #3	$181.53	7.507%	$195.1575	$195.16	$195.15	$195.20
Purchase #4	$54.32	8.856%	$59.1306	$59.13	$59.15	$59.10
Purchase #5	$141.82	9.363%	$155.0986	$155.10	$155.10	$155.10
Purchase #6	$9.86	8.267%	$10.6751	$10.68	$10.70	$10.70
Purchase #7	$31.61	6.820%	$33.7658	$33.77	$33.75	$33.80
7 purchase totals =	$742.42		$801.5457	$801.56	$801.55	$801.60