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	$129.66	10.807%	$143.6724	$143.67	$143.65	$143.70
Purchase #2	$10.63	5.236%	$11.1866	$11.19	$11.20	$11.20
Purchase #3	$9.30	6.632%	$9.9168	$9.92	$9.90	$9.90
Purchase #4	$219.56	4.133%	$228.6344	$228.63	$228.65	$228.60
Purchase #5	$213.44	11.624%	$238.2503	$238.25	$238.25	$238.30
Purchase #6	$217.83	12.120%	$244.231	$244.23	$244.25	$244.20
Purchase #7	$169.59	9.332%	$185.4161	$185.42	$185.40	$185.40
7 purchase totals =	$970.01		$1,061.3076	$1,061.31	$1,061.30	$1,061.30