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	$187.73	11.459%	$209.242	$209.24	$209.25	$209.20
Purchase #2	$41.35	12.609%	$46.5638	$46.56	$46.55	$46.60
Purchase #3	$207.28	4.751%	$217.1279	$217.13	$217.15	$217.10
Purchase #4	$95.47	4.776%	$100.0296	$100.03	$100.05	$100.00
Purchase #5	$103.90	8.531%	$112.7637	$112.76	$112.75	$112.80
Purchase #6	$117.73	11.730%	$131.5397	$131.54	$131.55	$131.50
Purchase #7	$187.25	5.478%	$197.5076	$197.51	$197.50	$197.50
7 purchase totals =	$940.71		$1,014.7743	$1,014.77	$1,014.80	$1,014.70