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	$174.25	5.595%	$183.9993	$184.00	$184.00	$184.00
Purchase #2	$143.28	6.507%	$152.6032	$152.60	$152.60	$152.60
Purchase #3	$93.57	12.296%	$105.0754	$105.08	$105.10	$105.10
Purchase #4	$142.54	5.118%	$149.8352	$149.84	$149.85	$149.80
Purchase #5	$67.81	5.267%	$71.3816	$71.38	$71.40	$71.40
Purchase #6	$40.72	7.497%	$43.7728	$43.77	$43.75	$43.80
Purchase #7	$139.78	13.426%	$158.5469	$158.55	$158.55	$158.50
7 purchase totals =	$801.95		$865.2144	$865.22	$865.25	$865.20