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	$111.75	10.450%	$123.4279	$123.43	$123.45	$123.40
Purchase #2	$7.57	4.288%	$7.8946	$7.89	$7.90	$7.90
Purchase #3	$236.73	6.860%	$252.9697	$252.97	$252.95	$253.00
Purchase #4	$54.81	8.124%	$59.2628	$59.26	$59.25	$59.30
Purchase #5	$242.72	11.390%	$270.3658	$270.37	$270.35	$270.40
Purchase #6	$138.56	10.133%	$152.6003	$152.60	$152.60	$152.60
Purchase #7	$242.31	6.502%	$258.065	$258.07	$258.05	$258.10
7 purchase totals =	$1,034.45		$1,124.5861	$1,124.59	$1,124.55	$1,124.70