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	$99.62	7.647%	$107.2379	$107.24	$107.25	$107.20
Purchase #2	$212.38	11.641%	$237.1032	$237.10	$237.10	$237.10
Purchase #3	$29.56	5.434%	$31.1663	$31.17	$31.15	$31.20
Purchase #4	$123.73	6.321%	$131.551	$131.55	$131.55	$131.60
Purchase #5	$156.42	8.256%	$169.334	$169.33	$169.35	$169.30
Purchase #6	$136.72	9.685%	$149.9613	$149.96	$149.95	$150.00
Purchase #7	$182.53	7.436%	$196.1029	$196.10	$196.10	$196.10
7 purchase totals =	$940.96		$1,022.4566	$1,022.45	$1,022.45	$1,022.50