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	$206.56	9.802%	$226.807	$226.81	$226.80	$226.80
Purchase #2	$7.43	11.665%	$8.2967	$8.30	$8.30	$8.30
Purchase #3	$23.45	8.766%	$25.5056	$25.51	$25.50	$25.50
Purchase #4	$11.56	7.404%	$12.4159	$12.42	$12.40	$12.40
Purchase #5	$97.57	7.847%	$105.2263	$105.23	$105.25	$105.20
Purchase #6	$44.33	8.809%	$48.235	$48.24	$48.25	$48.20
Purchase #7	$53.67	10.693%	$59.4089	$59.41	$59.40	$59.40
7 purchase totals =	$444.57		$485.8954	$485.92	$485.90	$485.80