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	$176.78	11.134%	$196.4627	$196.46	$196.45	$196.50
Purchase #2	$145.91	4.685%	$152.7459	$152.75	$152.75	$152.70
Purchase #3	$72.91	12.511%	$82.0318	$82.03	$82.05	$82.00
Purchase #4	$236.75	6.498%	$252.134	$252.13	$252.15	$252.10
Purchase #5	$86.56	7.376%	$92.9447	$92.94	$92.95	$92.90
Purchase #6	$77.78	4.701%	$81.4364	$81.44	$81.45	$81.40
Purchase #7	$210.40	8.328%	$227.9221	$227.92	$227.90	$227.90
7 purchase totals =	$1,007.09		$1,085.6776	$1,085.67	$1,085.70	$1,085.50