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	$176.59	4.739%	$184.9586	$184.96	$184.95	$185.00
Purchase #2	$9.36	10.450%	$10.3381	$10.34	$10.35	$10.30
Purchase #3	$92.83	4.328%	$96.8477	$96.85	$96.85	$96.80
Purchase #4	$13.43	13.590%	$15.2551	$15.26	$15.25	$15.30
Purchase #5	$51.86	5.828%	$54.8824	$54.88	$54.90	$54.90
Purchase #6	$29.52	9.818%	$32.4183	$32.42	$32.40	$32.40
Purchase #7	$94.75	4.757%	$99.2573	$99.26	$99.25	$99.30
7 purchase totals =	$468.34		$493.9575	$493.97	$493.95	$494.00