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	$121.82	10.372%	$134.4552	$134.46	$134.45	$134.50
Purchase #2	$198.84	6.251%	$211.2695	$211.27	$211.25	$211.30
Purchase #3	$136.32	4.373%	$142.2813	$142.28	$142.30	$142.30
Purchase #4	$31.33	11.409%	$34.9044	$34.90	$34.90	$34.90
Purchase #5	$144.77	6.126%	$153.6386	$153.64	$153.65	$153.60
Purchase #6	$167.71	10.572%	$185.4403	$185.44	$185.45	$185.40
Purchase #7	$177.35	12.297%	$199.1587	$199.16	$199.15	$199.20
7 purchase totals =	$978.14		$1,061.1480	$1,061.15	$1,061.15	$1,061.20