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	$228.76	3.719%	$237.2676	$237.27	$237.25	$237.30
Purchase #2	$158.72	9.818%	$174.3031	$174.30	$174.30	$174.30
Purchase #3	$188.66	6.309%	$200.5626	$200.56	$200.55	$200.60
Purchase #4	$170.26	10.256%	$187.7219	$187.72	$187.70	$187.70
Purchase #5	$24.80	10.436%	$27.3881	$27.39	$27.40	$27.40
Purchase #6	$221.32	13.216%	$250.5697	$250.57	$250.55	$250.60
Purchase #7	$6.50	5.402%	$6.8511	$6.85	$6.85	$6.90
7 purchase totals =	$999.02		$1,084.6641	$1,084.66	$1,084.60	$1,084.80