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	$118.39	7.221%	$126.9389	$126.94	$126.95	$126.90
Purchase #2	$42.49	10.191%	$46.8202	$46.82	$46.80	$46.80
Purchase #3	$50.49	9.757%	$55.4163	$55.42	$55.40	$55.40
Purchase #4	$99.34	5.710%	$105.0123	$105.01	$105.00	$105.00
Purchase #5	$225.70	5.773%	$238.7297	$238.73	$238.75	$238.70
Purchase #6	$242.53	10.250%	$267.3893	$267.39	$267.40	$267.40
Purchase #7	$78.77	8.793%	$85.6962	$85.70	$85.70	$85.70
7 purchase totals =	$857.71		$926.0029	$926.01	$926.00	$925.90