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	$143.65	12.775%	$162.0013	$162.00	$162.00	$162.00
Purchase #2	$224.57	12.246%	$252.0708	$252.07	$252.05	$252.10
Purchase #3	$75.33	10.681%	$83.376	$83.38	$83.40	$83.40
Purchase #4	$117.56	8.348%	$127.3739	$127.37	$127.35	$127.40
Purchase #5	$141.57	5.116%	$148.8127	$148.81	$148.80	$148.80
Purchase #6	$78.82	13.832%	$89.7224	$89.72	$89.70	$89.70
Purchase #7	$173.57	9.613%	$190.2553	$190.26	$190.25	$190.30
7 purchase totals =	$955.07		$1,053.6124	$1,053.61	$1,053.55	$1,053.70