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	$182.51	7.651%	$196.4738	$196.47	$196.45	$196.50
Purchase #2	$170.91	8.138%	$184.8187	$184.82	$184.80	$184.80
Purchase #3	$166.30	11.110%	$184.7759	$184.78	$184.80	$184.80
Purchase #4	$184.48	9.381%	$201.7861	$201.79	$201.80	$201.80
Purchase #5	$193.82	11.351%	$215.8205	$215.82	$215.80	$215.80
Purchase #6	$12.67	13.812%	$14.42	$14.42	$14.40	$14.40
Purchase #7	$99.98	13.750%	$113.7273	$113.73	$113.75	$113.70
7 purchase totals =	$1,010.67		$1,111.8223	$1,111.83	$1,111.80	$1,111.80