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	$216.71	7.515%	$232.9958	$233.00	$233.00	$233.00
Purchase #2	$95.87	13.593%	$108.9016	$108.90	$108.90	$108.90
Purchase #3	$120.67	10.662%	$133.5358	$133.54	$133.55	$133.50
Purchase #4	$238.26	5.161%	$250.5566	$250.56	$250.55	$250.60
Purchase #5	$66.89	8.121%	$72.3221	$72.32	$72.30	$72.30
Purchase #6	$91.57	3.525%	$94.7978	$94.80	$94.80	$94.80
Purchase #7	$145.69	7.368%	$156.4244	$156.42	$156.40	$156.40
7 purchase totals =	$975.66		$1,049.5341	$1,049.54	$1,049.50	$1,049.50