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	$185.55	13.378%	$210.3729	$210.37	$210.35	$210.40
Purchase #2	$83.32	3.828%	$86.5095	$86.51	$86.50	$86.50
Purchase #3	$87.77	8.720%	$95.4235	$95.42	$95.40	$95.40
Purchase #4	$181.65	9.435%	$198.7887	$198.79	$198.80	$198.80
Purchase #5	$78.82	4.610%	$82.4536	$82.45	$82.45	$82.50
Purchase #6	$183.33	12.791%	$206.7797	$206.78	$206.80	$206.80
Purchase #7	$174.70	4.847%	$183.1677	$183.17	$183.15	$183.20
7 purchase totals =	$975.14		$1,063.4956	$1,063.49	$1,063.45	$1,063.60