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	$114.67	4.440%	$119.7613	$119.76	$119.75	$119.80
Purchase #2	$168.88	4.482%	$176.4492	$176.45	$176.45	$176.40
Purchase #3	$59.59	4.845%	$62.4771	$62.48	$62.50	$62.50
Purchase #4	$220.89	13.405%	$250.5003	$250.50	$250.50	$250.50
Purchase #5	$181.74	7.370%	$195.1342	$195.13	$195.15	$195.10
Purchase #6	$95.85	9.734%	$105.18	$105.18	$105.20	$105.20
Purchase #7	$44.82	7.712%	$48.2765	$48.28	$48.30	$48.30
7 purchase totals =	$886.44		$957.7786	$957.78	$957.85	$957.80