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	$203.65	9.822%	$223.6525	$223.65	$223.65	$223.70
Purchase #2	$25.98	11.212%	$28.8929	$28.89	$28.90	$28.90
Purchase #3	$248.54	9.806%	$272.9118	$272.91	$272.90	$272.90
Purchase #4	$66.42	10.685%	$73.517	$73.52	$73.50	$73.50
Purchase #5	$220.79	11.559%	$246.3111	$246.31	$246.30	$246.30
Purchase #6	$88.68	11.695%	$99.0511	$99.05	$99.05	$99.10
Purchase #7	$167.72	12.521%	$188.7202	$188.72	$188.70	$188.70
7 purchase totals =	$1,021.78		$1,133.0566	$1,133.05	$1,133.00	$1,133.10