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	$98.41	13.587%	$111.781	$111.78	$111.80	$111.80
Purchase #2	$176.58	13.245%	$199.968	$199.97	$199.95	$200.00
Purchase #3	$125.88	12.213%	$141.2537	$141.25	$141.25	$141.30
Purchase #4	$119.51	5.582%	$126.181	$126.18	$126.20	$126.20
Purchase #5	$179.86	6.858%	$192.1948	$192.19	$192.20	$192.20
Purchase #6	$137.54	9.722%	$150.9116	$150.91	$150.90	$150.90
Purchase #7	$82.67	10.399%	$91.2669	$91.27	$91.25	$91.30
7 purchase totals =	$920.45		$1,013.5570	$1,013.55	$1,013.55	$1,013.70