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	$130.43	10.151%	$143.6699	$143.67	$143.65	$143.70
Purchase #2	$24.79	3.295%	$25.6068	$25.61	$25.60	$25.60
Purchase #3	$92.64	5.248%	$97.5017	$97.50	$97.50	$97.50
Purchase #4	$53.59	3.270%	$55.3424	$55.34	$55.35	$55.30
Purchase #5	$21.26	5.250%	$22.3762	$22.38	$22.40	$22.40
Purchase #6	$155.27	4.535%	$162.3115	$162.31	$162.30	$162.30
Purchase #7	$55.27	13.337%	$62.6414	$62.64	$62.65	$62.60
7 purchase totals =	$533.25		$569.4499	$569.45	$569.45	$569.40