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	$184.45	12.688%	$207.853	$207.85	$207.85	$207.90
Purchase #2	$145.63	13.328%	$165.0396	$165.04	$165.05	$165.00
Purchase #3	$47.48	9.325%	$51.9075	$51.91	$51.90	$51.90
Purchase #4	$229.83	6.424%	$244.5943	$244.59	$244.60	$244.60
Purchase #5	$56.50	10.275%	$62.3054	$62.31	$62.30	$62.30
Purchase #6	$137.42	3.581%	$142.341	$142.34	$142.35	$142.30
Purchase #7	$153.30	9.523%	$167.8988	$167.90	$167.90	$167.90
7 purchase totals =	$954.61		$1,041.9396	$1,041.94	$1,041.95	$1,041.90