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	$58.68	5.126%	$61.6879	$61.69	$61.70	$61.70
Purchase #2	$208.81	6.722%	$222.8462	$222.85	$222.85	$222.80
Purchase #3	$180.87	5.482%	$190.7853	$190.79	$190.80	$190.80
Purchase #4	$85.27	6.534%	$90.8415	$90.84	$90.85	$90.80
Purchase #5	$152.54	13.293%	$172.8171	$172.82	$172.80	$172.80
Purchase #6	$205.89	7.315%	$220.9509	$220.95	$220.95	$221.00
Purchase #7	$81.27	3.532%	$84.1405	$84.14	$84.15	$84.10
7 purchase totals =	$973.33		$1,044.0694	$1,044.08	$1,044.10	$1,044.00