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	$156.52	4.103%	$162.942	$162.94	$162.95	$162.90
Purchase #2	$41.39	5.410%	$43.6292	$43.63	$43.65	$43.60
Purchase #3	$39.86	12.589%	$44.878	$44.88	$44.90	$44.90
Purchase #4	$171.60	7.837%	$185.0483	$185.05	$185.05	$185.00
Purchase #5	$215.27	5.243%	$226.5566	$226.56	$226.55	$226.60
Purchase #6	$62.82	13.521%	$71.3139	$71.31	$71.30	$71.30
Purchase #7	$142.36	9.360%	$155.6849	$155.68	$155.70	$155.70
7 purchase totals =	$829.82		$890.0529	$890.05	$890.10	$890.00