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	$76.72	7.321%	$82.3367	$82.34	$82.35	$82.30
Purchase #2	$32.57	5.323%	$34.3037	$34.30	$34.30	$34.30
Purchase #3	$138.32	4.505%	$144.5513	$144.55	$144.55	$144.60
Purchase #4	$186.45	11.419%	$207.7407	$207.74	$207.75	$207.70
Purchase #5	$235.64	5.289%	$248.103	$248.10	$248.10	$248.10
Purchase #6	$189.84	3.629%	$196.7293	$196.73	$196.75	$196.70
Purchase #7	$94.74	8.548%	$102.8384	$102.84	$102.85	$102.80
7 purchase totals =	$954.28		$1,016.6031	$1,016.60	$1,016.65	$1,016.50