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	$147.71	10.202%	$162.7794	$162.78	$162.80	$162.80
Purchase #2	$205.38	7.348%	$220.4713	$220.47	$220.45	$220.50
Purchase #3	$55.80	11.279%	$62.0937	$62.09	$62.10	$62.10
Purchase #4	$143.51	7.634%	$154.4656	$154.47	$154.45	$154.50
Purchase #5	$219.42	8.843%	$238.8233	$238.82	$238.80	$238.80
Purchase #6	$90.80	9.638%	$99.5513	$99.55	$99.55	$99.60
Purchase #7	$159.57	8.542%	$173.2005	$173.20	$173.20	$173.20
7 purchase totals =	$1,022.19		$1,111.3851	$1,111.38	$1,111.35	$1,111.50