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	$65.32	10.247%	$72.0133	$72.01	$72.00	$72.00
Purchase #2	$224.57	11.142%	$249.5916	$249.59	$249.60	$249.60
Purchase #3	$43.39	5.365%	$45.7179	$45.72	$45.70	$45.70
Purchase #4	$181.26	3.426%	$187.47	$187.47	$187.45	$187.50
Purchase #5	$250.60	7.517%	$269.4376	$269.44	$269.45	$269.40
Purchase #6	$216.67	12.511%	$243.7776	$243.78	$243.80	$243.80
Purchase #7	$43.38	7.737%	$46.7363	$46.74	$46.75	$46.70
7 purchase totals =	$1,025.19		$1,114.7443	$1,114.75	$1,114.75	$1,114.70