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	$41.86	10.486%	$46.2494	$46.25	$46.25	$46.20
Purchase #2	$114.89	8.136%	$124.2375	$124.24	$124.25	$124.20
Purchase #3	$154.44	13.494%	$175.2801	$175.28	$175.30	$175.30
Purchase #4	$241.80	8.513%	$262.3844	$262.38	$262.40	$262.40
Purchase #5	$46.92	13.868%	$53.4269	$53.43	$53.45	$53.40
Purchase #6	$56.79	4.373%	$59.2734	$59.27	$59.25	$59.30
Purchase #7	$38.49	4.806%	$40.3398	$40.34	$40.35	$40.30
7 purchase totals =	$695.19		$761.1915	$761.19	$761.25	$761.10