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	$10.83	5.616%	$11.4382	$11.44	$11.45	$11.40
Purchase #2	$250.67	12.314%	$281.5375	$281.54	$281.55	$281.50
Purchase #3	$105.68	5.176%	$111.15	$111.15	$111.15	$111.20
Purchase #4	$48.92	10.803%	$54.2048	$54.20	$54.20	$54.20
Purchase #5	$191.52	4.269%	$199.696	$199.70	$199.70	$199.70
Purchase #6	$181.36	4.108%	$188.8103	$188.81	$188.80	$188.80
Purchase #7	$173.41	5.507%	$182.9597	$182.96	$182.95	$183.00
7 purchase totals =	$962.39		$1,029.7965	$1,029.80	$1,029.80	$1,029.80