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	$62.29	7.723%	$67.1007	$67.10	$67.10	$67.10
Purchase #2	$107.82	3.454%	$111.5441	$111.54	$111.55	$111.50
Purchase #3	$142.92	9.687%	$156.7647	$156.76	$156.75	$156.80
Purchase #4	$112.32	10.245%	$123.8272	$123.83	$123.85	$123.80
Purchase #5	$183.57	9.148%	$200.363	$200.36	$200.35	$200.40
Purchase #6	$105.42	8.161%	$114.0233	$114.02	$114.00	$114.00
Purchase #7	$237.66	6.302%	$252.6373	$252.64	$252.65	$252.60
7 purchase totals =	$952.00		$1,026.2603	$1,026.25	$1,026.25	$1,026.20