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	$216.46	8.481%	$234.818	$234.82	$234.80	$234.80
Purchase #2	$94.32	12.376%	$105.993	$105.99	$106.00	$106.00
Purchase #3	$39.54	10.421%	$43.6605	$43.66	$43.65	$43.70
Purchase #4	$195.31	10.648%	$216.1066	$216.11	$216.10	$216.10
Purchase #5	$153.61	4.236%	$160.1169	$160.12	$160.10	$160.10
Purchase #6	$192.68	5.218%	$202.734	$202.73	$202.75	$202.70
Purchase #7	$124.90	13.602%	$141.8889	$141.89	$141.90	$141.90
7 purchase totals =	$1,016.82		$1,105.3179	$1,105.32	$1,105.30	$1,105.30