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	$217.44	11.737%	$242.9609	$242.96	$242.95	$243.00
Purchase #2	$144.39	3.409%	$149.3123	$149.31	$149.30	$149.30
Purchase #3	$65.52	11.151%	$72.8261	$72.83	$72.85	$72.80
Purchase #4	$218.61	5.159%	$229.8881	$229.89	$229.90	$229.90
Purchase #5	$41.87	4.415%	$43.7186	$43.72	$43.70	$43.70
Purchase #6	$224.59	4.826%	$235.4287	$235.43	$235.45	$235.40
Purchase #7	$85.76	4.266%	$89.4185	$89.42	$89.40	$89.40
7 purchase totals =	$998.18		$1,063.5532	$1,063.56	$1,063.55	$1,063.50