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	$168.38	7.828%	$181.5608	$181.56	$181.55	$181.60
Purchase #2	$98.52	13.149%	$111.4744	$111.47	$111.45	$111.50
Purchase #3	$52.78	6.671%	$56.301	$56.30	$56.30	$56.30
Purchase #4	$173.51	4.739%	$181.7326	$181.73	$181.75	$181.70
Purchase #5	$218.84	12.219%	$245.5801	$245.58	$245.60	$245.60
Purchase #6	$201.78	5.768%	$213.4187	$213.42	$213.40	$213.40
Purchase #7	$25.25	6.572%	$26.9094	$26.91	$26.90	$26.90
7 purchase totals =	$939.06		$1,016.9770	$1,016.97	$1,016.95	$1,017.00