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	$147.78	4.439%	$154.34	$154.34	$154.35	$154.30
Purchase #2	$15.89	3.541%	$16.4527	$16.45	$16.45	$16.50
Purchase #3	$104.62	7.655%	$112.6287	$112.63	$112.65	$112.60
Purchase #4	$135.49	5.141%	$142.4555	$142.46	$142.45	$142.50
Purchase #5	$190.92	10.607%	$211.1709	$211.17	$211.15	$211.20
Purchase #6	$50.77	13.632%	$57.691	$57.69	$57.70	$57.70
Purchase #7	$66.46	9.203%	$72.5763	$72.58	$72.60	$72.60
7 purchase totals =	$711.93		$767.3151	$767.32	$767.35	$767.40