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	$72.49	5.736%	$76.648	$76.65	$76.65	$76.60
Purchase #2	$33.75	9.651%	$37.0072	$37.01	$37.00	$37.00
Purchase #3	$142.31	5.626%	$150.3164	$150.32	$150.30	$150.30
Purchase #4	$67.66	7.323%	$72.6147	$72.61	$72.60	$72.60
Purchase #5	$101.97	11.866%	$114.0698	$114.07	$114.05	$114.10
Purchase #6	$46.60	3.229%	$48.1047	$48.10	$48.10	$48.10
Purchase #7	$241.26	6.273%	$256.3942	$256.39	$256.40	$256.40
7 purchase totals =	$706.04		$755.1550	$755.15	$755.10	$755.10