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	$134.98	5.162%	$141.9477	$141.95	$141.95	$141.90
Purchase #2	$217.63	9.689%	$238.7162	$238.72	$238.70	$238.70
Purchase #3	$83.72	12.827%	$94.4588	$94.46	$94.45	$94.50
Purchase #4	$89.92	12.284%	$100.9658	$100.97	$100.95	$101.00
Purchase #5	$182.93	5.455%	$192.9088	$192.91	$192.90	$192.90
Purchase #6	$119.81	7.860%	$129.2271	$129.23	$129.25	$129.20
Purchase #7	$146.50	12.862%	$165.3428	$165.34	$165.35	$165.30
7 purchase totals =	$975.49		$1,063.5672	$1,063.58	$1,063.55	$1,063.50