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	$126.38	3.297%	$130.5467	$130.55	$130.55	$130.50
Purchase #2	$38.44	13.127%	$43.486	$43.49	$43.50	$43.50
Purchase #3	$56.39	8.675%	$61.2818	$61.28	$61.30	$61.30
Purchase #4	$23.30	13.438%	$26.4311	$26.43	$26.45	$26.40
Purchase #5	$139.77	8.105%	$151.0984	$151.10	$151.10	$151.10
Purchase #6	$249.99	5.149%	$262.862	$262.86	$262.85	$262.90
Purchase #7	$73.45	4.159%	$76.5048	$76.50	$76.50	$76.50
7 purchase totals =	$707.72		$752.2108	$752.21	$752.25	$752.20