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	$198.54	8.576%	$215.5668	$215.57	$215.55	$215.60
Purchase #2	$103.94	8.200%	$112.4631	$112.46	$112.45	$112.50
Purchase #3	$225.40	4.379%	$235.2703	$235.27	$235.25	$235.30
Purchase #4	$175.50	8.375%	$190.1981	$190.20	$190.20	$190.20
Purchase #5	$79.78	8.108%	$86.2486	$86.25	$86.25	$86.20
Purchase #6	$184.64	8.554%	$200.4341	$200.43	$200.45	$200.40
Purchase #7	$40.96	10.675%	$45.3325	$45.33	$45.35	$45.30
7 purchase totals =	$1,008.76		$1,085.5135	$1,085.51	$1,085.50	$1,085.50