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	$69.33	10.420%	$76.5542	$76.55	$76.55	$76.60
Purchase #2	$93.94	5.809%	$99.397	$99.40	$99.40	$99.40
Purchase #3	$183.25	9.218%	$200.142	$200.14	$200.15	$200.10
Purchase #4	$189.49	11.706%	$211.6717	$211.67	$211.65	$211.70
Purchase #5	$150.90	9.758%	$165.6248	$165.62	$165.60	$165.60
Purchase #6	$142.27	12.645%	$160.26	$160.26	$160.25	$160.30
Purchase #7	$241.39	5.143%	$253.8047	$253.80	$253.80	$253.80
7 purchase totals =	$1,070.57		$1,167.4544	$1,167.44	$1,167.40	$1,167.50