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	3.787%	$43.4452	$43.45	$43.45	$43.40
Purchase #2	$33.96	12.573%	$38.2298	$38.23	$38.25	$38.20
Purchase #3	$100.99	12.793%	$113.9097	$113.91	$113.90	$113.90
Purchase #4	$179.60	9.344%	$196.3818	$196.38	$196.40	$196.40
Purchase #5	$218.52	4.451%	$228.2463	$228.25	$228.25	$228.20
Purchase #6	$217.95	12.382%	$244.9366	$244.94	$244.95	$244.90
Purchase #7	$119.27	9.474%	$130.5696	$130.57	$130.55	$130.60
7 purchase totals =	$912.15		$995.7190	$995.73	$995.75	$995.60