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	$122.51	3.627%	$126.9534	$126.95	$126.95	$127.00
Purchase #2	$50.81	4.595%	$53.1447	$53.14	$53.15	$53.10
Purchase #3	$165.33	10.504%	$182.6963	$182.70	$182.70	$182.70
Purchase #4	$44.41	5.459%	$46.8343	$46.83	$46.85	$46.80
Purchase #5	$150.85	6.118%	$160.079	$160.08	$160.10	$160.10
Purchase #6	$95.32	5.441%	$100.5064	$100.51	$100.50	$100.50
Purchase #7	$38.69	9.279%	$42.28	$42.28	$42.30	$42.30
7 purchase totals =	$667.92		$712.4941	$712.49	$712.55	$712.50