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	$160.51	6.761%	$171.3621	$171.36	$171.35	$171.40
Purchase #2	$188.88	13.510%	$214.3977	$214.40	$214.40	$214.40
Purchase #3	$18.69	5.832%	$19.78	$19.78	$19.80	$19.80
Purchase #4	$151.84	10.311%	$167.4962	$167.50	$167.50	$167.50
Purchase #5	$163.89	6.803%	$175.0394	$175.04	$175.05	$175.00
Purchase #6	$105.54	3.375%	$109.102	$109.10	$109.10	$109.10
Purchase #7	$175.28	10.443%	$193.5845	$193.58	$193.60	$193.60
7 purchase totals =	$964.63		$1,050.7619	$1,050.76	$1,050.80	$1,050.80