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	$217.69	12.333%	$244.5377	$244.54	$244.55	$244.50
Purchase #2	$230.50	13.582%	$261.8065	$261.81	$261.80	$261.80
Purchase #3	$43.53	7.214%	$46.6703	$46.67	$46.65	$46.70
Purchase #4	$125.66	13.380%	$142.4733	$142.47	$142.45	$142.50
Purchase #5	$226.40	7.449%	$243.2645	$243.26	$243.25	$243.30
Purchase #6	$209.36	11.538%	$233.516	$233.52	$233.50	$233.50
Purchase #7	$214.87	6.662%	$229.1846	$229.18	$229.20	$229.20
7 purchase totals =	$1,268.01		$1,401.4529	$1,401.45	$1,401.40	$1,401.50