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	$175.39	11.287%	$195.1863	$195.19	$195.20	$195.20
Purchase #2	$67.87	6.147%	$72.042	$72.04	$72.05	$72.00
Purchase #3	$48.94	9.342%	$53.512	$53.51	$53.50	$53.50
Purchase #4	$213.67	6.648%	$227.8748	$227.87	$227.85	$227.90
Purchase #5	$248.49	12.631%	$279.8768	$279.88	$279.90	$279.90
Purchase #6	$99.83	4.780%	$104.6019	$104.60	$104.60	$104.60
Purchase #7	$120.87	5.360%	$127.3486	$127.35	$127.35	$127.30
7 purchase totals =	$975.06		$1,060.4424	$1,060.44	$1,060.45	$1,060.40