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	$60.42	11.227%	$67.2034	$67.20	$67.20	$67.20
Purchase #2	$130.64	3.695%	$135.4671	$135.47	$135.45	$135.50
Purchase #3	$120.84	4.151%	$125.8561	$125.86	$125.85	$125.90
Purchase #4	$151.42	9.441%	$165.7156	$165.72	$165.70	$165.70
Purchase #5	$246.43	11.212%	$274.0597	$274.06	$274.05	$274.10
Purchase #6	$129.94	7.166%	$139.2515	$139.25	$139.25	$139.30
Purchase #7	$179.93	9.268%	$196.6059	$196.61	$196.60	$196.60
7 purchase totals =	$1,019.62		$1,104.1593	$1,104.17	$1,104.10	$1,104.30