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	$153.82	5.838%	$162.8	$162.80	$162.80	$162.80
Purchase #2	$74.41	12.693%	$83.8549	$83.85	$83.85	$83.90
Purchase #3	$146.39	13.452%	$166.0824	$166.08	$166.10	$166.10
Purchase #4	$146.40	12.430%	$164.5975	$164.60	$164.60	$164.60
Purchase #5	$158.26	6.392%	$168.376	$168.38	$168.40	$168.40
Purchase #6	$145.49	3.552%	$150.6578	$150.66	$150.65	$150.70
Purchase #7	$101.29	9.788%	$111.2043	$111.20	$111.20	$111.20
7 purchase totals =	$926.06		$1,007.5729	$1,007.57	$1,007.60	$1,007.70