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	$116.40	13.796%	$132.4585	$132.46	$132.45	$132.50
Purchase #2	$9.48	6.152%	$10.0632	$10.06	$10.05	$10.10
Purchase #3	$171.52	3.219%	$177.0412	$177.04	$177.05	$177.00
Purchase #4	$18.46	7.722%	$19.8855	$19.89	$19.90	$19.90
Purchase #5	$99.29	6.409%	$105.6535	$105.65	$105.65	$105.70
Purchase #6	$133.90	13.673%	$152.2081	$152.21	$152.20	$152.20
Purchase #7	$46.88	11.140%	$52.1024	$52.10	$52.10	$52.10
7 purchase totals =	$595.93		$649.4124	$649.41	$649.40	$649.50