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	$184.78	9.410%	$202.1678	$202.17	$202.15	$202.20
Purchase #2	$64.89	11.850%	$72.5795	$72.58	$72.60	$72.60
Purchase #3	$219.83	3.162%	$226.781	$226.78	$226.80	$226.80
Purchase #4	$142.37	6.281%	$151.3123	$151.31	$151.30	$151.30
Purchase #5	$16.73	11.326%	$18.6248	$18.62	$18.60	$18.60
Purchase #6	$90.82	5.566%	$95.875	$95.88	$95.90	$95.90
Purchase #7	$187.82	4.115%	$195.5488	$195.55	$195.55	$195.50
7 purchase totals =	$907.24		$962.8892	$962.89	$962.90	$962.90