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	$123.96	5.379%	$130.6278	$130.63	$130.65	$130.60
Purchase #2	$81.34	5.290%	$85.6429	$85.64	$85.65	$85.60
Purchase #3	$202.26	10.806%	$224.1162	$224.12	$224.10	$224.10
Purchase #4	$191.40	8.679%	$208.0116	$208.01	$208.00	$208.00
Purchase #5	$53.74	11.488%	$59.9137	$59.91	$59.90	$59.90
Purchase #6	$137.34	3.220%	$141.7623	$141.76	$141.75	$141.80
Purchase #7	$157.45	9.571%	$172.5195	$172.52	$172.50	$172.50
7 purchase totals =	$947.49		$1,022.5940	$1,022.59	$1,022.55	$1,022.50