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	$180.61	13.838%	$205.6028	$205.60	$205.60	$205.60
Purchase #2	$5.46	6.424%	$5.8108	$5.81	$5.80	$5.80
Purchase #3	$116.52	13.740%	$132.5298	$132.53	$132.55	$132.50
Purchase #4	$244.54	10.371%	$269.9012	$269.90	$269.90	$269.90
Purchase #5	$83.53	5.404%	$88.044	$88.04	$88.05	$88.00
Purchase #6	$140.31	3.201%	$144.8013	$144.80	$144.80	$144.80
Purchase #7	$209.76	13.766%	$238.6356	$238.64	$238.65	$238.60
7 purchase totals =	$980.73		$1,085.3255	$1,085.32	$1,085.35	$1,085.20