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	$84.29	9.574%	$92.3599	$92.36	$92.35	$92.40
Purchase #2	$162.78	11.763%	$181.9278	$181.93	$181.95	$181.90
Purchase #3	$153.85	3.859%	$159.7871	$159.79	$159.80	$159.80
Purchase #4	$46.45	4.413%	$48.4998	$48.50	$48.50	$48.50
Purchase #5	$250.44	7.367%	$268.8899	$268.89	$268.90	$268.90
Purchase #6	$203.71	10.843%	$225.7983	$225.80	$225.80	$225.80
Purchase #7	$84.39	7.707%	$90.8939	$90.89	$90.90	$90.90
7 purchase totals =	$985.91		$1,068.1567	$1,068.16	$1,068.20	$1,068.20