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	$41.64	5.566%	$43.9577	$43.96	$43.95	$44.00
Purchase #2	$94.81	10.375%	$104.6465	$104.65	$104.65	$104.60
Purchase #3	$112.50	13.683%	$127.8934	$127.89	$127.90	$127.90
Purchase #4	$219.62	9.329%	$240.1083	$240.11	$240.10	$240.10
Purchase #5	$30.27	8.287%	$32.7785	$32.78	$32.80	$32.80
Purchase #6	$60.51	6.649%	$64.5333	$64.53	$64.55	$64.50
Purchase #7	$128.28	10.786%	$142.1163	$142.12	$142.10	$142.10
7 purchase totals =	$687.63		$756.0340	$756.04	$756.05	$756.00