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	$168.66	4.760%	$176.6882	$176.69	$176.70	$176.70
Purchase #2	$188.78	9.298%	$206.3328	$206.33	$206.35	$206.30
Purchase #3	$177.97	7.501%	$191.3195	$191.32	$191.30	$191.30
Purchase #4	$91.85	9.147%	$100.2515	$100.25	$100.25	$100.30
Purchase #5	$79.98	5.841%	$84.6516	$84.65	$84.65	$84.70
Purchase #6	$183.60	9.171%	$200.438	$200.44	$200.45	$200.40
Purchase #7	$100.63	4.637%	$105.2962	$105.30	$105.30	$105.30
7 purchase totals =	$991.47		$1,064.9778	$1,064.98	$1,065.00	$1,065.00