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	$48.74	7.591%	$52.4399	$52.44	$52.45	$52.40
Purchase #2	$66.62	5.367%	$70.1955	$70.20	$70.20	$70.20
Purchase #3	$167.86	13.450%	$190.4372	$190.44	$190.45	$190.40
Purchase #4	$198.56	13.400%	$225.167	$225.17	$225.15	$225.20
Purchase #5	$242.90	9.552%	$266.1018	$266.10	$266.10	$266.10
Purchase #6	$163.80	5.573%	$172.9286	$172.93	$172.95	$172.90
Purchase #7	$52.37	7.431%	$56.2616	$56.26	$56.25	$56.30
7 purchase totals =	$940.85		$1,033.5316	$1,033.54	$1,033.55	$1,033.50