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	$182.25	4.725%	$190.8613	$190.86	$190.85	$190.90
Purchase #2	$234.40	11.158%	$260.5544	$260.55	$260.55	$260.60
Purchase #3	$47.88	9.525%	$52.4406	$52.44	$52.45	$52.40
Purchase #4	$123.67	5.259%	$130.1738	$130.17	$130.15	$130.20
Purchase #5	$111.52	4.227%	$116.234	$116.23	$116.25	$116.20
Purchase #6	$117.55	11.331%	$130.8696	$130.87	$130.85	$130.90
Purchase #7	$130.75	11.377%	$145.6254	$145.63	$145.65	$145.60
7 purchase totals =	$948.02		$1,026.7591	$1,026.75	$1,026.75	$1,026.80