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	$161.94	9.827%	$177.8538	$177.85	$177.85	$177.90
Purchase #2	$196.30	13.544%	$222.8869	$222.89	$222.90	$222.90
Purchase #3	$97.50	3.476%	$100.8891	$100.89	$100.90	$100.90
Purchase #4	$187.35	12.180%	$210.1692	$210.17	$210.15	$210.20
Purchase #5	$10.95	5.746%	$11.5792	$11.58	$11.60	$11.60
Purchase #6	$199.53	6.130%	$211.7612	$211.76	$211.75	$211.80
Purchase #7	$146.76	13.705%	$166.8735	$166.87	$166.85	$166.90
7 purchase totals =	$1,000.33		$1,102.0129	$1,102.01	$1,102.00	$1,102.20