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	$214.40	9.109%	$233.9297	$233.93	$233.95	$233.90
Purchase #2	$160.66	3.639%	$166.5064	$166.51	$166.50	$166.50
Purchase #3	$80.62	6.316%	$85.712	$85.71	$85.70	$85.70
Purchase #4	$92.76	11.132%	$103.086	$103.09	$103.10	$103.10
Purchase #5	$174.99	12.394%	$196.6783	$196.68	$196.70	$196.70
Purchase #6	$111.71	3.243%	$115.3328	$115.33	$115.35	$115.30
Purchase #7	$90.32	4.187%	$94.1017	$94.10	$94.10	$94.10
7 purchase totals =	$925.46		$995.3469	$995.35	$995.40	$995.30