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	$208.62	5.572%	$220.2443	$220.24	$220.25	$220.20
Purchase #2	$131.79	3.711%	$136.6807	$136.68	$136.70	$136.70
Purchase #3	$166.77	12.292%	$187.2694	$187.27	$187.25	$187.30
Purchase #4	$225.50	11.822%	$252.1586	$252.16	$252.15	$252.20
Purchase #5	$172.79	13.116%	$195.4531	$195.45	$195.45	$195.50
Purchase #6	$55.66	7.661%	$59.9241	$59.92	$59.90	$59.90
Purchase #7	$143.59	3.563%	$148.7061	$148.71	$148.70	$148.70
7 purchase totals =	$1,104.72		$1,200.4363	$1,200.43	$1,200.40	$1,200.50