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	$187.98	7.240%	$201.5898	$201.59	$201.60	$201.60
Purchase #2	$48.66	10.151%	$53.5995	$53.60	$53.60	$53.60
Purchase #3	$204.48	8.817%	$222.509	$222.51	$222.50	$222.50
Purchase #4	$166.32	12.108%	$186.458	$186.46	$186.45	$186.50
Purchase #5	$161.45	10.439%	$178.3038	$178.30	$178.30	$178.30
Purchase #6	$56.28	7.506%	$60.5044	$60.50	$60.50	$60.50
Purchase #7	$162.86	6.618%	$173.6381	$173.64	$173.65	$173.60
7 purchase totals =	$988.03		$1,076.6026	$1,076.60	$1,076.60	$1,076.60