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	$160.96	8.141%	$174.0638	$174.06	$174.05	$174.10
Purchase #2	$207.95	12.466%	$233.873	$233.87	$233.85	$233.90
Purchase #3	$9.52	12.413%	$10.7017	$10.70	$10.70	$10.70
Purchase #4	$111.93	10.361%	$123.5271	$123.53	$123.55	$123.50
Purchase #5	$62.56	7.796%	$67.4372	$67.44	$67.45	$67.40
Purchase #6	$179.99	11.169%	$200.0931	$200.09	$200.10	$200.10
Purchase #7	$225.85	5.761%	$238.8612	$238.86	$238.85	$238.90
7 purchase totals =	$958.76		$1,048.5571	$1,048.55	$1,048.55	$1,048.60