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	$173.51	13.268%	$196.5313	$196.53	$196.55	$196.50
Purchase #2	$156.40	7.208%	$167.6733	$167.67	$167.65	$167.70
Purchase #3	$22.84	13.769%	$25.9848	$25.98	$26.00	$26.00
Purchase #4	$196.26	10.262%	$216.4002	$216.40	$216.40	$216.40
Purchase #5	$151.49	11.217%	$168.4826	$168.48	$168.50	$168.50
Purchase #6	$197.56	5.578%	$208.5799	$208.58	$208.60	$208.60
Purchase #7	$56.28	8.567%	$61.1015	$61.10	$61.10	$61.10
7 purchase totals =	$954.34		$1,044.7536	$1,044.74	$1,044.80	$1,044.80