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	$172.63	13.750%	$196.3666	$196.37	$196.35	$196.40
Purchase #2	$157.32	3.585%	$162.9599	$162.96	$162.95	$163.00
Purchase #3	$55.53	12.827%	$62.6528	$62.65	$62.65	$62.70
Purchase #4	$191.61	12.773%	$216.0843	$216.08	$216.10	$216.10
Purchase #5	$42.32	3.169%	$43.6611	$43.66	$43.65	$43.70
Purchase #6	$139.54	11.827%	$156.0434	$156.04	$156.05	$156.00
Purchase #7	$173.81	10.657%	$192.3329	$192.33	$192.35	$192.30
7 purchase totals =	$932.76		$1,030.1010	$1,030.09	$1,030.10	$1,030.20