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	$100.43	11.400%	$111.879	$111.88	$111.90	$111.90
Purchase #2	$141.76	5.297%	$149.269	$149.27	$149.25	$149.30
Purchase #3	$229.49	4.644%	$240.1475	$240.15	$240.15	$240.10
Purchase #4	$19.73	5.396%	$20.7946	$20.79	$20.80	$20.80
Purchase #5	$218.88	6.429%	$232.9518	$232.95	$232.95	$233.00
Purchase #6	$164.59	6.377%	$175.0859	$175.09	$175.10	$175.10
Purchase #7	$153.42	8.598%	$166.6111	$166.61	$166.60	$166.60
7 purchase totals =	$1,028.30		$1,096.7389	$1,096.74	$1,096.75	$1,096.80