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	$68.72	10.740%	$76.1005	$76.10	$76.10	$76.10
Purchase #2	$200.31	3.575%	$207.4711	$207.47	$207.45	$207.50
Purchase #3	$212.51	3.222%	$219.3571	$219.36	$219.35	$219.40
Purchase #4	$78.43	8.607%	$85.1805	$85.18	$85.20	$85.20
Purchase #5	$165.37	4.503%	$172.8166	$172.82	$172.80	$172.80
Purchase #6	$98.40	5.155%	$103.4725	$103.47	$103.45	$103.50
Purchase #7	$148.83	11.179%	$165.4677	$165.47	$165.45	$165.50
7 purchase totals =	$972.57		$1,029.8660	$1,029.87	$1,029.80	$1,030.00