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	$151.98	13.590%	$172.6341	$172.63	$172.65	$172.60
Purchase #2	$38.54	12.258%	$43.2642	$43.26	$43.25	$43.30
Purchase #3	$68.68	4.710%	$71.9148	$71.91	$71.90	$71.90
Purchase #4	$54.96	8.386%	$59.5689	$59.57	$59.55	$59.60
Purchase #5	$219.43	12.412%	$246.6657	$246.67	$246.65	$246.70
Purchase #6	$187.88	13.128%	$212.5449	$212.54	$212.55	$212.50
Purchase #7	$219.82	10.526%	$242.9583	$242.96	$242.95	$243.00
7 purchase totals =	$941.29		$1,049.5509	$1,049.54	$1,049.50	$1,049.60