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	$74.69	10.142%	$82.2651	$82.27	$82.25	$82.30
Purchase #2	$21.65	7.837%	$23.3467	$23.35	$23.35	$23.30
Purchase #3	$40.97	5.602%	$43.2651	$43.27	$43.25	$43.30
Purchase #4	$226.33	3.168%	$233.5001	$233.50	$233.50	$233.50
Purchase #5	$65.69	10.703%	$72.7208	$72.72	$72.70	$72.70
Purchase #6	$218.38	13.565%	$248.0032	$248.00	$248.00	$248.00
Purchase #7	$203.94	13.308%	$231.0803	$231.08	$231.10	$231.10
7 purchase totals =	$851.65		$934.1813	$934.19	$934.15	$934.20