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	$119.43	6.447%	$127.1297	$127.13	$127.15	$127.10
Purchase #2	$9.66	7.503%	$10.3848	$10.38	$10.40	$10.40
Purchase #3	$7.46	13.556%	$8.4713	$8.47	$8.45	$8.50
Purchase #4	$78.77	8.661%	$85.5923	$85.59	$85.60	$85.60
Purchase #5	$35.33	10.380%	$38.9973	$39.00	$39.00	$39.00
Purchase #6	$118.80	6.613%	$126.6562	$126.66	$126.65	$126.70
Purchase #7	$89.46	7.553%	$96.2169	$96.22	$96.20	$96.20
7 purchase totals =	$458.91		$493.4485	$493.45	$493.45	$493.50