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	$199.93	8.498%	$216.9201	$216.92	$216.90	$216.90
Purchase #2	$249.51	5.191%	$262.4621	$262.46	$262.45	$262.50
Purchase #3	$30.28	12.132%	$33.9536	$33.95	$33.95	$34.00
Purchase #4	$63.83	13.411%	$72.3902	$72.39	$72.40	$72.40
Purchase #5	$171.62	4.352%	$179.0889	$179.09	$179.10	$179.10
Purchase #6	$99.81	10.194%	$109.9846	$109.98	$110.00	$110.00
Purchase #7	$130.44	5.155%	$137.1642	$137.16	$137.15	$137.20
7 purchase totals =	$945.42		$1,011.9637	$1,011.95	$1,011.95	$1,012.10