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	$153.72	5.223%	$161.7488	$161.75	$161.75	$161.70
Purchase #2	$244.78	13.530%	$277.8987	$277.90	$277.90	$277.90
Purchase #3	$190.49	7.659%	$205.0796	$205.08	$205.10	$205.10
Purchase #4	$97.94	7.627%	$105.4099	$105.41	$105.40	$105.40
Purchase #5	$30.59	6.618%	$32.6144	$32.61	$32.60	$32.60
Purchase #6	$179.97	13.856%	$204.9066	$204.91	$204.90	$204.90
Purchase #7	$64.90	10.517%	$71.7255	$71.73	$71.75	$71.70
7 purchase totals =	$962.39		$1,059.3835	$1,059.39	$1,059.40	$1,059.30