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	$147.64	10.289%	$162.8307	$162.83	$162.85	$162.80
Purchase #2	$148.64	11.521%	$165.7648	$165.76	$165.75	$165.80
Purchase #3	$134.90	5.219%	$141.9404	$141.94	$141.95	$141.90
Purchase #4	$235.71	5.320%	$248.2498	$248.25	$248.25	$248.20
Purchase #5	$20.73	4.425%	$21.6473	$21.65	$21.65	$21.60
Purchase #6	$57.59	9.643%	$63.1434	$63.14	$63.15	$63.10
Purchase #7	$148.44	10.574%	$164.136	$164.14	$164.15	$164.10
7 purchase totals =	$893.65		$967.7124	$967.71	$967.75	$967.50