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	$174.70	7.293%	$187.4409	$187.44	$187.45	$187.40
Purchase #2	$169.32	12.440%	$190.3834	$190.38	$190.40	$190.40
Purchase #3	$80.73	6.561%	$86.0267	$86.03	$86.05	$86.00
Purchase #4	$57.85	3.201%	$59.7018	$59.70	$59.70	$59.70
Purchase #5	$187.47	11.513%	$209.0534	$209.05	$209.05	$209.10
Purchase #6	$188.26	11.349%	$209.6256	$209.63	$209.65	$209.60
Purchase #7	$245.45	8.551%	$266.4384	$266.44	$266.45	$266.40
7 purchase totals =	$1,103.78		$1,208.6702	$1,208.67	$1,208.75	$1,208.60