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	$92.45	3.405%	$95.5979	$95.60	$95.60	$95.60
Purchase #2	$42.45	3.120%	$43.7744	$43.77	$43.75	$43.80
Purchase #3	$49.89	5.515%	$52.6414	$52.64	$52.65	$52.60
Purchase #4	$16.41	4.329%	$17.1204	$17.12	$17.10	$17.10
Purchase #5	$68.79	12.789%	$77.5876	$77.59	$77.60	$77.60
Purchase #6	$20.55	3.707%	$21.3118	$21.31	$21.30	$21.30
Purchase #7	$90.61	11.850%	$101.3473	$101.35	$101.35	$101.30
7 purchase totals =	$381.15		$409.3808	$409.38	$409.35	$409.30