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	$210.59	4.329%	$219.7064	$219.71	$219.70	$219.70
Purchase #2	$25.51	9.240%	$27.8671	$27.87	$27.85	$27.90
Purchase #3	$94.31	6.457%	$100.3996	$100.40	$100.40	$100.40
Purchase #4	$250.82	3.238%	$258.9416	$258.94	$258.95	$258.90
Purchase #5	$111.69	11.463%	$124.493	$124.49	$124.50	$124.50
Purchase #6	$213.32	11.340%	$237.5105	$237.51	$237.50	$237.50
Purchase #7	$214.54	13.760%	$244.0607	$244.06	$244.05	$244.10
7 purchase totals =	$1,120.78		$1,212.9789	$1,212.98	$1,212.95	$1,213.00