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	$155.92	4.402%	$162.7836	$162.78	$162.80	$162.80
Purchase #2	$6.92	13.521%	$7.8557	$7.86	$7.85	$7.90
Purchase #3	$112.75	13.282%	$127.7255	$127.73	$127.75	$127.70
Purchase #4	$43.39	13.371%	$49.1917	$49.19	$49.20	$49.20
Purchase #5	$96.45	10.293%	$106.3776	$106.38	$106.40	$106.40
Purchase #6	$69.53	4.434%	$72.613	$72.61	$72.60	$72.60
Purchase #7	$162.78	6.602%	$173.5267	$173.53	$173.55	$173.50
7 purchase totals =	$647.74		$700.0738	$700.08	$700.15	$700.10