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	$141.35	4.671%	$147.9525	$147.95	$147.95	$148.00
Purchase #2	$147.76	8.371%	$160.129	$160.13	$160.15	$160.10
Purchase #3	$167.53	10.832%	$185.6768	$185.68	$185.70	$185.70
Purchase #4	$196.60	3.801%	$204.0728	$204.07	$204.05	$204.10
Purchase #5	$27.67	12.390%	$31.0983	$31.10	$31.10	$31.10
Purchase #6	$154.60	5.320%	$162.8247	$162.82	$162.80	$162.80
Purchase #7	$63.34	7.133%	$67.858	$67.86	$67.85	$67.90
7 purchase totals =	$898.85		$959.6121	$959.61	$959.60	$959.70