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	$114.96	13.743%	$130.759	$130.76	$130.75	$130.80
Purchase #2	$37.68	6.863%	$40.266	$40.27	$40.25	$40.30
Purchase #3	$38.33	7.616%	$41.2492	$41.25	$41.25	$41.20
Purchase #4	$77.80	9.569%	$85.2447	$85.24	$85.25	$85.20
Purchase #5	$32.36	3.244%	$33.4098	$33.41	$33.40	$33.40
Purchase #6	$46.31	11.470%	$51.6218	$51.62	$51.60	$51.60
Purchase #7	$56.28	12.351%	$63.2311	$63.23	$63.25	$63.20
7 purchase totals =	$403.72		$445.7816	$445.78	$445.75	$445.70