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	$164.95	5.125%	$173.4037	$173.40	$173.40	$173.40
Purchase #2	$206.60	6.627%	$220.2914	$220.29	$220.30	$220.30
Purchase #3	$157.54	6.688%	$168.0763	$168.08	$168.10	$168.10
Purchase #4	$243.36	11.473%	$271.2807	$271.28	$271.30	$271.30
Purchase #5	$41.55	5.553%	$43.8573	$43.86	$43.85	$43.90
Purchase #6	$69.40	4.136%	$72.2704	$72.27	$72.25	$72.30
Purchase #7	$154.41	9.589%	$169.2164	$169.22	$169.20	$169.20
7 purchase totals =	$1,037.81		$1,118.3962	$1,118.40	$1,118.40	$1,118.50