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	$107.55	4.453%	$112.3392	$112.34	$112.35	$112.30
Purchase #2	$240.78	13.588%	$273.4972	$273.50	$273.50	$273.50
Purchase #3	$136.77	4.421%	$142.8166	$142.82	$142.80	$142.80
Purchase #4	$49.94	6.196%	$53.0343	$53.03	$53.05	$53.00
Purchase #5	$70.39	4.561%	$73.6005	$73.60	$73.60	$73.60
Purchase #6	$177.61	12.669%	$200.1114	$200.11	$200.10	$200.10
Purchase #7	$154.50	11.279%	$171.9261	$171.93	$171.95	$171.90
7 purchase totals =	$937.54		$1,027.3253	$1,027.33	$1,027.35	$1,027.20