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	$219.46	7.740%	$236.4462	$236.45	$236.45	$236.40
Purchase #2	$208.42	11.830%	$233.0761	$233.08	$233.10	$233.10
Purchase #3	$168.38	9.102%	$183.7059	$183.71	$183.70	$183.70
Purchase #4	$5.74	11.452%	$6.3973	$6.40	$6.40	$6.40
Purchase #5	$132.76	7.483%	$142.6944	$142.69	$142.70	$142.70
Purchase #6	$141.42	13.490%	$160.4976	$160.50	$160.50	$160.50
Purchase #7	$207.86	12.194%	$233.2064	$233.21	$233.20	$233.20
7 purchase totals =	$1,084.04		$1,196.0239	$1,196.04	$1,196.05	$1,196.00