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	$219.79	10.104%	$241.9976	$242.00	$242.00	$242.00
Purchase #2	$175.40	6.767%	$187.2693	$187.27	$187.25	$187.30
Purchase #3	$102.98	8.598%	$111.8342	$111.83	$111.85	$111.80
Purchase #4	$69.28	3.334%	$71.5898	$71.59	$71.60	$71.60
Purchase #5	$142.87	5.459%	$150.6693	$150.67	$150.65	$150.70
Purchase #6	$243.46	7.661%	$262.1115	$262.11	$262.10	$262.10
Purchase #7	$79.56	12.407%	$89.431	$89.43	$89.45	$89.40
7 purchase totals =	$1,033.34		$1,114.9027	$1,114.90	$1,114.90	$1,114.90