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	$170.83	13.588%	$194.0424	$194.04	$194.05	$194.00
Purchase #2	$72.58	8.771%	$78.946	$78.95	$78.95	$78.90
Purchase #3	$239.77	6.322%	$254.9283	$254.93	$254.95	$254.90
Purchase #4	$245.88	12.630%	$276.9346	$276.93	$276.95	$276.90
Purchase #5	$134.39	8.663%	$146.0322	$146.03	$146.05	$146.00
Purchase #6	$162.71	13.320%	$184.383	$184.38	$184.40	$184.40
Purchase #7	$145.49	4.834%	$152.523	$152.52	$152.50	$152.50
7 purchase totals =	$1,171.65		$1,287.7895	$1,287.78	$1,287.85	$1,287.60