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	$208.90	11.657%	$233.2515	$233.25	$233.25	$233.30
Purchase #2	$21.55	13.118%	$24.3769	$24.38	$24.40	$24.40
Purchase #3	$80.56	11.184%	$89.5698	$89.57	$89.55	$89.60
Purchase #4	$250.25	11.314%	$278.5633	$278.56	$278.55	$278.60
Purchase #5	$235.53	12.282%	$264.4578	$264.46	$264.45	$264.50
Purchase #6	$46.53	12.730%	$52.4533	$52.45	$52.45	$52.50
Purchase #7	$242.84	6.286%	$258.1049	$258.10	$258.10	$258.10
7 purchase totals =	$1,086.16		$1,200.7775	$1,200.77	$1,200.75	$1,201.00