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	$205.50	4.387%	$214.5153	$214.52	$214.50	$214.50
Purchase #2	$29.92	13.469%	$33.9499	$33.95	$33.95	$33.90
Purchase #3	$144.37	11.194%	$160.5308	$160.53	$160.55	$160.50
Purchase #4	$188.40	4.151%	$196.2205	$196.22	$196.20	$196.20
Purchase #5	$116.95	13.687%	$132.9569	$132.96	$132.95	$133.00
Purchase #6	$137.73	4.397%	$143.786	$143.79	$143.80	$143.80
Purchase #7	$248.90	13.618%	$282.7952	$282.80	$282.80	$282.80
7 purchase totals =	$1,071.77		$1,164.7546	$1,164.77	$1,164.75	$1,164.70