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	$111.64	4.446%	$116.6035	$116.60	$116.60	$116.60
Purchase #2	$140.88	5.182%	$148.1804	$148.18	$148.20	$148.20
Purchase #3	$26.90	13.243%	$30.4624	$30.46	$30.45	$30.50
Purchase #4	$140.79	3.254%	$145.3713	$145.37	$145.35	$145.40
Purchase #5	$233.73	3.582%	$242.1022	$242.10	$242.10	$242.10
Purchase #6	$98.26	13.357%	$111.3846	$111.38	$111.40	$111.40
Purchase #7	$213.83	5.173%	$224.8914	$224.89	$224.90	$224.90
7 purchase totals =	$966.03		$1,018.9958	$1,018.98	$1,019.00	$1,019.10