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	$69.86	3.699%	$72.4441	$72.44	$72.45	$72.40
Purchase #2	$248.81	5.753%	$263.124	$263.12	$263.10	$263.10
Purchase #3	$16.83	13.223%	$19.0554	$19.06	$19.05	$19.10
Purchase #4	$243.63	4.709%	$255.1025	$255.10	$255.10	$255.10
Purchase #5	$176.28	9.173%	$192.4502	$192.45	$192.45	$192.50
Purchase #6	$207.67	4.179%	$216.3485	$216.35	$216.35	$216.30
Purchase #7	$81.76	4.466%	$85.4114	$85.41	$85.40	$85.40
7 purchase totals =	$1,044.84		$1,103.9361	$1,103.93	$1,103.90	$1,103.90