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	$32.26	10.747%	$35.727	$35.73	$35.75	$35.70
Purchase #2	$155.82	9.475%	$170.5839	$170.58	$170.60	$170.60
Purchase #3	$152.98	6.474%	$162.8839	$162.88	$162.90	$162.90
Purchase #4	$52.28	11.127%	$58.0972	$58.10	$58.10	$58.10
Purchase #5	$195.27	13.322%	$221.2839	$221.28	$221.30	$221.30
Purchase #6	$144.33	4.821%	$151.2881	$151.29	$151.30	$151.30
Purchase #7	$244.31	7.127%	$261.722	$261.72	$261.70	$261.70
7 purchase totals =	$977.25		$1,061.5860	$1,061.58	$1,061.65	$1,061.60