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	$92.80	4.418%	$96.8999	$96.90	$96.90	$96.90
Purchase #2	$216.42	5.626%	$228.5958	$228.60	$228.60	$228.60
Purchase #3	$159.64	10.825%	$176.921	$176.92	$176.90	$176.90
Purchase #4	$137.26	11.541%	$153.1012	$153.10	$153.10	$153.10
Purchase #5	$62.70	13.734%	$71.3112	$71.31	$71.30	$71.30
Purchase #6	$232.77	6.712%	$248.3935	$248.39	$248.40	$248.40
Purchase #7	$153.64	10.160%	$169.2498	$169.25	$169.25	$169.20
7 purchase totals =	$1,055.23		$1,144.4724	$1,144.47	$1,144.45	$1,144.40