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	$164.39	13.312%	$186.2736	$186.27	$186.25	$186.30
Purchase #2	$182.49	5.589%	$192.6894	$192.69	$192.70	$192.70
Purchase #3	$82.60	3.730%	$85.681	$85.68	$85.70	$85.70
Purchase #4	$140.82	3.718%	$146.0557	$146.06	$146.05	$146.10
Purchase #5	$231.36	7.736%	$249.258	$249.26	$249.25	$249.30
Purchase #6	$142.26	7.244%	$152.5653	$152.57	$152.55	$152.60
Purchase #7	$102.68	8.508%	$111.416	$111.42	$111.40	$111.40
7 purchase totals =	$1,046.60		$1,123.9390	$1,123.95	$1,123.90	$1,124.10