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	$160.59	9.791%	$176.3134	$176.31	$176.30	$176.30
Purchase #2	$52.51	3.746%	$54.477	$54.48	$54.50	$54.50
Purchase #3	$193.70	12.288%	$217.5019	$217.50	$217.50	$217.50
Purchase #4	$248.76	4.839%	$260.7975	$260.80	$260.80	$260.80
Purchase #5	$111.90	10.512%	$123.6629	$123.66	$123.65	$123.70
Purchase #6	$146.44	6.253%	$155.5969	$155.60	$155.60	$155.60
Purchase #7	$92.69	5.842%	$98.1049	$98.10	$98.10	$98.10
7 purchase totals =	$1,006.59		$1,086.4545	$1,086.45	$1,086.45	$1,086.50