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	$215.72	9.365%	$235.9222	$235.92	$235.90	$235.90
Purchase #2	$118.98	7.459%	$127.8547	$127.85	$127.85	$127.90
Purchase #3	$137.59	9.489%	$150.6459	$150.65	$150.65	$150.60
Purchase #4	$142.85	6.728%	$152.4609	$152.46	$152.45	$152.50
Purchase #5	$218.76	10.704%	$242.1761	$242.18	$242.20	$242.20
Purchase #6	$198.93	6.193%	$211.2497	$211.25	$211.25	$211.20
Purchase #7	$11.76	7.186%	$12.6051	$12.61	$12.60	$12.60
7 purchase totals =	$1,044.59		$1,132.9146	$1,132.92	$1,132.90	$1,132.90