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	$167.97	10.572%	$185.7278	$185.73	$185.75	$185.70
Purchase #2	$69.65	13.563%	$79.0966	$79.10	$79.10	$79.10
Purchase #3	$78.87	13.501%	$89.5182	$89.52	$89.50	$89.50
Purchase #4	$211.31	5.402%	$222.725	$222.73	$222.75	$222.70
Purchase #5	$101.29	13.225%	$114.6856	$114.69	$114.70	$114.70
Purchase #6	$67.62	10.663%	$74.8303	$74.83	$74.85	$74.80
Purchase #7	$220.80	6.381%	$234.8892	$234.89	$234.90	$234.90
7 purchase totals =	$917.51		$1,001.4727	$1,001.49	$1,001.55	$1,001.40