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	$185.50	13.713%	$210.9376	$210.94	$210.95	$210.90
Purchase #2	$90.82	6.105%	$96.3646	$96.36	$96.35	$96.40
Purchase #3	$71.29	5.433%	$75.1632	$75.16	$75.15	$75.20
Purchase #4	$30.83	10.125%	$33.9515	$33.95	$33.95	$34.00
Purchase #5	$134.70	5.333%	$141.8836	$141.88	$141.90	$141.90
Purchase #6	$212.25	4.622%	$222.0602	$222.06	$222.05	$222.10
Purchase #7	$216.50	6.463%	$230.4924	$230.49	$230.50	$230.50
7 purchase totals =	$941.89		$1,010.8531	$1,010.84	$1,010.85	$1,011.00