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	$195.86	6.844%	$209.2647	$209.26	$209.25	$209.30
Purchase #2	$214.27	13.353%	$242.8815	$242.88	$242.90	$242.90
Purchase #3	$103.40	6.831%	$110.4633	$110.46	$110.45	$110.50
Purchase #4	$110.75	3.438%	$114.5576	$114.56	$114.55	$114.60
Purchase #5	$204.32	4.439%	$213.3898	$213.39	$213.40	$213.40
Purchase #6	$107.61	5.548%	$113.5802	$113.58	$113.60	$113.60
Purchase #7	$56.84	4.330%	$59.3012	$59.30	$59.30	$59.30
7 purchase totals =	$993.05		$1,063.4383	$1,063.43	$1,063.45	$1,063.60