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	$207.40	4.808%	$217.3718	$217.37	$217.35	$217.40
Purchase #2	$34.33	3.426%	$35.5061	$35.51	$35.50	$35.50
Purchase #3	$114.75	3.360%	$118.6056	$118.61	$118.60	$118.60
Purchase #4	$91.85	10.376%	$101.3804	$101.38	$101.40	$101.40
Purchase #5	$51.78	3.770%	$53.7321	$53.73	$53.75	$53.70
Purchase #6	$212.49	3.592%	$220.1226	$220.12	$220.10	$220.10
Purchase #7	$236.62	8.116%	$255.8241	$255.82	$255.80	$255.80
7 purchase totals =	$949.22		$1,002.5427	$1,002.54	$1,002.50	$1,002.50