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	$58.87	10.314%	$64.9419	$64.94	$64.95	$64.90
Purchase #2	$185.56	13.691%	$210.965	$210.97	$210.95	$211.00
Purchase #3	$151.75	10.141%	$167.139	$167.14	$167.15	$167.10
Purchase #4	$247.74	13.579%	$281.3806	$281.38	$281.40	$281.40
Purchase #5	$59.83	11.873%	$66.9336	$66.93	$66.95	$66.90
Purchase #6	$147.51	7.385%	$158.4036	$158.40	$158.40	$158.40
Purchase #7	$88.59	9.403%	$96.9201	$96.92	$96.90	$96.90
7 purchase totals =	$939.85		$1,046.6838	$1,046.68	$1,046.70	$1,046.60