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	$219.60	9.321%	$240.0689	$240.07	$240.05	$240.10
Purchase #2	$171.55	4.439%	$179.1651	$179.17	$179.15	$179.20
Purchase #3	$36.27	4.494%	$37.9	$37.90	$37.90	$37.90
Purchase #4	$120.75	5.144%	$126.9614	$126.96	$126.95	$127.00
Purchase #5	$32.60	9.178%	$35.592	$35.59	$35.60	$35.60
Purchase #6	$106.79	8.716%	$116.0978	$116.10	$116.10	$116.10
Purchase #7	$249.84	12.580%	$281.2699	$281.27	$281.25	$281.30
7 purchase totals =	$937.40		$1,017.0551	$1,017.06	$1,017.00	$1,017.20