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	$176.87	11.803%	$197.746	$197.75	$197.75	$197.70
Purchase #2	$57.42	6.383%	$61.0851	$61.09	$61.10	$61.10
Purchase #3	$139.96	4.227%	$145.8761	$145.88	$145.90	$145.90
Purchase #4	$126.49	11.567%	$141.1211	$141.12	$141.10	$141.10
Purchase #5	$154.76	8.214%	$167.472	$167.47	$167.45	$167.50
Purchase #6	$96.89	7.195%	$103.8612	$103.86	$103.85	$103.90
Purchase #7	$244.67	8.248%	$264.8504	$264.85	$264.85	$264.90
7 purchase totals =	$997.06		$1,082.0119	$1,082.02	$1,082.00	$1,082.10