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	$148.41	3.520%	$153.634	$153.63	$153.65	$153.60
Purchase #2	$121.32	5.255%	$127.6954	$127.70	$127.70	$127.70
Purchase #3	$221.41	10.529%	$244.7223	$244.72	$244.70	$244.70
Purchase #4	$122.36	4.403%	$127.7475	$127.75	$127.75	$127.70
Purchase #5	$101.61	11.812%	$113.6122	$113.61	$113.60	$113.60
Purchase #6	$83.99	8.132%	$90.8201	$90.82	$90.80	$90.80
Purchase #7	$232.73	13.768%	$264.7723	$264.77	$264.75	$264.80
7 purchase totals =	$1,031.83		$1,123.0038	$1,123.00	$1,122.95	$1,122.90