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	$47.30	3.444%	$48.929	$48.93	$48.95	$48.90
Purchase #2	$150.34	4.621%	$157.2872	$157.29	$157.30	$157.30
Purchase #3	$106.63	5.857%	$112.8753	$112.88	$112.90	$112.90
Purchase #4	$54.30	8.857%	$59.1094	$59.11	$59.10	$59.10
Purchase #5	$83.26	5.516%	$87.8526	$87.85	$87.85	$87.90
Purchase #6	$35.36	6.307%	$37.5902	$37.59	$37.60	$37.60
Purchase #7	$235.51	3.689%	$244.198	$244.20	$244.20	$244.20
7 purchase totals =	$712.70		$747.8417	$747.85	$747.90	$747.90