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	$214.90	5.743%	$227.2417	$227.24	$227.25	$227.20
Purchase #2	$83.33	5.425%	$87.8507	$87.85	$87.85	$87.90
Purchase #3	$130.42	9.423%	$142.7095	$142.71	$142.70	$142.70
Purchase #4	$147.77	6.142%	$156.846	$156.85	$156.85	$156.80
Purchase #5	$244.34	3.294%	$252.3886	$252.39	$252.40	$252.40
Purchase #6	$208.29	6.524%	$221.8788	$221.88	$221.90	$221.90
Purchase #7	$204.83	3.365%	$211.7225	$211.72	$211.70	$211.70
7 purchase totals =	$1,233.88		$1,300.6378	$1,300.64	$1,300.65	$1,300.60