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	$10.34	8.545%	$11.2236	$11.22	$11.20	$11.20
Purchase #2	$126.72	4.640%	$132.5998	$132.60	$132.60	$132.60
Purchase #3	$169.79	6.607%	$181.008	$181.01	$181.00	$181.00
Purchase #4	$222.71	10.145%	$245.3039	$245.30	$245.30	$245.30
Purchase #5	$88.89	11.709%	$99.2981	$99.30	$99.30	$99.30
Purchase #6	$187.58	10.606%	$207.4747	$207.47	$207.45	$207.50
Purchase #7	$187.74	4.740%	$196.6389	$196.64	$196.65	$196.60
7 purchase totals =	$993.77		$1,073.5470	$1,073.54	$1,073.50	$1,073.50