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	$43.29	10.156%	$47.6865	$47.69	$47.70	$47.70
Purchase #2	$19.30	11.184%	$21.4585	$21.46	$21.45	$21.50
Purchase #3	$55.27	6.873%	$59.0687	$59.07	$59.05	$59.10
Purchase #4	$199.61	11.104%	$221.7747	$221.77	$221.75	$221.80
Purchase #5	$54.71	7.853%	$59.0064	$59.01	$59.00	$59.00
Purchase #6	$208.67	10.822%	$231.2523	$231.25	$231.25	$231.30
Purchase #7	$138.29	12.163%	$155.1102	$155.11	$155.10	$155.10
7 purchase totals =	$719.14		$795.3573	$795.36	$795.30	$795.50