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	$96.89	8.836%	$105.4512	$105.45	$105.45	$105.50
Purchase #2	$212.83	8.817%	$231.5952	$231.60	$231.60	$231.60
Purchase #3	$172.74	7.108%	$185.0184	$185.02	$185.00	$185.00
Purchase #4	$153.85	9.467%	$168.415	$168.42	$168.40	$168.40
Purchase #5	$170.38	7.737%	$183.5623	$183.56	$183.55	$183.60
Purchase #6	$199.82	9.301%	$218.4053	$218.41	$218.40	$218.40
Purchase #7	$149.39	13.859%	$170.094	$170.09	$170.10	$170.10
7 purchase totals =	$1,155.90		$1,262.5414	$1,262.55	$1,262.50	$1,262.60