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	$164.69	7.174%	$176.5049	$176.50	$176.50	$176.50
Purchase #2	$142.37	6.489%	$151.6084	$151.61	$151.60	$151.60
Purchase #3	$151.65	10.460%	$167.5126	$167.51	$167.50	$167.50
Purchase #4	$243.92	3.872%	$253.3646	$253.36	$253.35	$253.40
Purchase #5	$92.46	4.481%	$96.6031	$96.60	$96.60	$96.60
Purchase #6	$56.35	5.826%	$59.633	$59.63	$59.65	$59.60
Purchase #7	$236.73	9.866%	$260.0858	$260.09	$260.10	$260.10
7 purchase totals =	$1,088.17		$1,165.3124	$1,165.30	$1,165.30	$1,165.30