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	$141.67	9.841%	$155.6117	$155.61	$155.60	$155.60
Purchase #2	$221.53	11.768%	$247.5997	$247.60	$247.60	$247.60
Purchase #3	$146.67	3.852%	$152.3197	$152.32	$152.30	$152.30
Purchase #4	$149.44	6.711%	$159.4689	$159.47	$159.45	$159.50
Purchase #5	$225.36	12.298%	$253.0748	$253.07	$253.05	$253.10
Purchase #6	$82.82	7.503%	$89.034	$89.03	$89.05	$89.00
Purchase #7	$128.82	12.391%	$144.7821	$144.78	$144.80	$144.80
7 purchase totals =	$1,096.31		$1,201.8909	$1,201.88	$1,201.85	$1,201.90