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	$99.45	6.532%	$105.9461	$105.95	$105.95	$105.90
Purchase #2	$47.58	6.401%	$50.6256	$50.63	$50.65	$50.60
Purchase #3	$144.97	11.419%	$161.5241	$161.52	$161.50	$161.50
Purchase #4	$200.77	10.802%	$222.4572	$222.46	$222.45	$222.50
Purchase #5	$167.70	9.489%	$183.6131	$183.61	$183.60	$183.60
Purchase #6	$172.92	6.528%	$184.2082	$184.21	$184.20	$184.20
Purchase #7	$43.88	3.228%	$45.2964	$45.30	$45.30	$45.30
7 purchase totals =	$877.27		$953.6707	$953.68	$953.65	$953.60