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	$223.56	3.398%	$231.1566	$231.16	$231.15	$231.20
Purchase #2	$153.70	4.275%	$160.2707	$160.27	$160.25	$160.30
Purchase #3	$239.50	7.220%	$256.7919	$256.79	$256.80	$256.80
Purchase #4	$37.28	11.151%	$41.4371	$41.44	$41.45	$41.40
Purchase #5	$143.44	4.806%	$150.3337	$150.33	$150.35	$150.30
Purchase #6	$90.42	5.640%	$95.5197	$95.52	$95.50	$95.50
Purchase #7	$211.53	3.515%	$218.9653	$218.97	$218.95	$219.00
7 purchase totals =	$1,099.43		$1,154.4750	$1,154.48	$1,154.45	$1,154.50