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	$190.97	5.108%	$200.7247	$200.72	$200.70	$200.70
Purchase #2	$186.86	11.103%	$207.6071	$207.61	$207.60	$207.60
Purchase #3	$97.65	12.616%	$109.9695	$109.97	$109.95	$110.00
Purchase #4	$183.33	9.486%	$200.7207	$200.72	$200.70	$200.70
Purchase #5	$250.61	7.710%	$269.932	$269.93	$269.95	$269.90
Purchase #6	$112.76	5.759%	$119.2538	$119.25	$119.25	$119.30
Purchase #7	$132.74	11.793%	$148.394	$148.39	$148.40	$148.40
7 purchase totals =	$1,154.92		$1,256.6018	$1,256.59	$1,256.55	$1,256.60