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	$218.78	10.596%	$241.9619	$241.96	$241.95	$242.00
Purchase #2	$6.86	9.181%	$7.4898	$7.49	$7.50	$7.50
Purchase #3	$188.26	6.269%	$200.062	$200.06	$200.05	$200.10
Purchase #4	$194.45	5.678%	$205.4909	$205.49	$205.50	$205.50
Purchase #5	$196.63	7.710%	$211.7902	$211.79	$211.80	$211.80
Purchase #6	$102.90	6.700%	$109.7943	$109.79	$109.80	$109.80
Purchase #7	$49.88	11.470%	$55.6012	$55.60	$55.60	$55.60
7 purchase totals =	$957.76		$1,032.1903	$1,032.18	$1,032.20	$1,032.30