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	$53.95	10.300%	$59.5069	$59.51	$59.50	$59.50
Purchase #2	$168.83	5.429%	$177.9958	$178.00	$178.00	$178.00
Purchase #3	$138.73	11.208%	$154.2789	$154.28	$154.30	$154.30
Purchase #4	$68.29	6.767%	$72.9112	$72.91	$72.90	$72.90
Purchase #5	$182.56	11.644%	$203.8173	$203.82	$203.80	$203.80
Purchase #6	$205.61	9.616%	$225.3815	$225.38	$225.40	$225.40
Purchase #7	$235.52	3.180%	$243.0095	$243.01	$243.00	$243.00
7 purchase totals =	$1,053.49		$1,136.9011	$1,136.91	$1,136.90	$1,136.90