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	$185.69	4.363%	$193.7917	$193.79	$193.80	$193.80
Purchase #2	$21.83	3.292%	$22.5486	$22.55	$22.55	$22.50
Purchase #3	$39.67	9.548%	$43.4577	$43.46	$43.45	$43.50
Purchase #4	$195.77	10.589%	$216.5001	$216.50	$216.50	$216.50
Purchase #5	$15.53	11.369%	$17.2956	$17.30	$17.30	$17.30
Purchase #6	$123.74	3.688%	$128.3035	$128.30	$128.30	$128.30
Purchase #7	$98.87	10.859%	$109.6063	$109.61	$109.60	$109.60
7 purchase totals =	$681.10		$731.5035	$731.51	$731.50	$731.50