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	$211.54	10.275%	$233.2757	$233.28	$233.30	$233.30
Purchase #2	$225.27	5.314%	$237.2408	$237.24	$237.25	$237.20
Purchase #3	$114.96	7.700%	$123.8119	$123.81	$123.80	$123.80
Purchase #4	$111.36	5.419%	$117.3946	$117.39	$117.40	$117.40
Purchase #5	$89.25	3.564%	$92.4309	$92.43	$92.45	$92.40
Purchase #6	$27.92	10.543%	$30.8636	$30.86	$30.85	$30.90
Purchase #7	$216.41	7.708%	$233.0909	$233.09	$233.10	$233.10
7 purchase totals =	$996.71		$1,068.1084	$1,068.10	$1,068.15	$1,068.10