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	$182.38	9.467%	$199.6459	$199.65	$199.65	$199.60
Purchase #2	$86.36	5.727%	$91.3058	$91.31	$91.30	$91.30
Purchase #3	$226.28	3.177%	$233.4689	$233.47	$233.45	$233.50
Purchase #4	$44.69	6.518%	$47.6029	$47.60	$47.60	$47.60
Purchase #5	$96.83	6.840%	$103.4532	$103.45	$103.45	$103.50
Purchase #6	$153.83	8.544%	$166.9732	$166.97	$166.95	$167.00
Purchase #7	$249.48	7.843%	$269.0467	$269.05	$269.05	$269.00
7 purchase totals =	$1,039.85		$1,111.4966	$1,111.50	$1,111.45	$1,111.50