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	$176.43	10.415%	$194.8052	$194.81	$194.80	$194.80
Purchase #2	$74.82	6.761%	$79.8786	$79.88	$79.90	$79.90
Purchase #3	$52.80	11.793%	$59.0267	$59.03	$59.05	$59.00
Purchase #4	$112.91	3.203%	$116.5265	$116.53	$116.55	$116.50
Purchase #5	$84.90	12.307%	$95.3486	$95.35	$95.35	$95.30
Purchase #6	$93.29	12.508%	$104.9587	$104.96	$104.95	$105.00
Purchase #7	$144.28	4.579%	$150.8866	$150.89	$150.90	$150.90
7 purchase totals =	$739.43		$801.4309	$801.45	$801.50	$801.40