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	$32.60	9.415%	$35.6693	$35.67	$35.65	$35.70
Purchase #2	$175.53	11.668%	$196.0108	$196.01	$196.00	$196.00
Purchase #3	$154.52	11.824%	$172.7904	$172.79	$172.80	$172.80
Purchase #4	$105.37	5.617%	$111.2886	$111.29	$111.30	$111.30
Purchase #5	$82.70	11.692%	$92.3693	$92.37	$92.35	$92.40
Purchase #6	$72.54	5.212%	$76.3208	$76.32	$76.30	$76.30
Purchase #7	$47.47	4.765%	$49.7319	$49.73	$49.75	$49.70
7 purchase totals =	$670.73		$734.1811	$734.18	$734.15	$734.20