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	$212.83	4.479%	$222.3627	$222.36	$222.35	$222.40
Purchase #2	$10.83	10.128%	$11.9269	$11.93	$11.95	$11.90
Purchase #3	$81.49	11.854%	$91.1498	$91.15	$91.15	$91.10
Purchase #4	$143.90	13.193%	$162.8847	$162.88	$162.90	$162.90
Purchase #5	$209.75	13.724%	$238.5361	$238.54	$238.55	$238.50
Purchase #6	$221.72	6.691%	$236.5553	$236.56	$236.55	$236.60
Purchase #7	$202.54	13.306%	$229.49	$229.49	$229.50	$229.50
7 purchase totals =	$1,083.06		$1,192.9055	$1,192.91	$1,192.95	$1,192.90