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	$23.53	9.248%	$25.7061	$25.71	$25.70	$25.70
Purchase #2	$80.72	5.504%	$85.1628	$85.16	$85.15	$85.20
Purchase #3	$164.94	11.757%	$184.332	$184.33	$184.35	$184.30
Purchase #4	$74.44	10.773%	$82.4594	$82.46	$82.45	$82.50
Purchase #5	$212.96	6.718%	$227.2667	$227.27	$227.25	$227.30
Purchase #6	$143.89	6.141%	$152.7263	$152.73	$152.75	$152.70
Purchase #7	$248.84	7.753%	$268.1326	$268.13	$268.15	$268.10
7 purchase totals =	$949.32		$1,025.7859	$1,025.79	$1,025.80	$1,025.80