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	$47.54	13.481%	$53.9489	$53.95	$53.95	$53.90
Purchase #2	$139.99	8.128%	$151.3684	$151.37	$151.35	$151.40
Purchase #3	$144.40	8.673%	$156.9238	$156.92	$156.90	$156.90
Purchase #4	$215.71	10.518%	$238.3984	$238.40	$238.40	$238.40
Purchase #5	$53.28	9.181%	$58.1716	$58.17	$58.15	$58.20
Purchase #6	$83.73	9.333%	$91.5445	$91.54	$91.55	$91.50
Purchase #7	$248.35	6.428%	$264.3139	$264.31	$264.30	$264.30
7 purchase totals =	$933.00		$1,014.6695	$1,014.66	$1,014.60	$1,014.60