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	$182.81	4.157%	$190.4094	$190.41	$190.40	$190.40
Purchase #2	$5.81	8.633%	$6.3116	$6.31	$6.30	$6.30
Purchase #3	$228.25	12.184%	$256.06	$256.06	$256.05	$256.10
Purchase #4	$146.45	13.624%	$166.4023	$166.40	$166.40	$166.40
Purchase #5	$141.82	9.225%	$154.9029	$154.90	$154.90	$154.90
Purchase #6	$188.61	9.868%	$207.222	$207.22	$207.20	$207.20
Purchase #7	$154.89	4.597%	$162.0103	$162.01	$162.00	$162.00
7 purchase totals =	$1,048.64		$1,143.3185	$1,143.31	$1,143.25	$1,143.30