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	$184.88	4.748%	$193.6581	$193.66	$193.65	$193.70
Purchase #2	$207.83	3.704%	$215.528	$215.53	$215.55	$215.50
Purchase #3	$152.68	9.564%	$167.2823	$167.28	$167.30	$167.30
Purchase #4	$19.51	12.568%	$21.962	$21.96	$21.95	$22.00
Purchase #5	$231.88	4.326%	$241.9111	$241.91	$241.90	$241.90
Purchase #6	$136.72	5.652%	$144.4474	$144.45	$144.45	$144.40
Purchase #7	$124.82	5.315%	$131.4542	$131.45	$131.45	$131.50
7 purchase totals =	$1,058.32		$1,116.2431	$1,116.24	$1,116.25	$1,116.30