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	$149.51	8.778%	$162.634	$162.63	$162.65	$162.60
Purchase #2	$176.43	11.308%	$196.3807	$196.38	$196.40	$196.40
Purchase #3	$72.29	8.487%	$78.4253	$78.43	$78.45	$78.40
Purchase #4	$205.30	8.525%	$222.8018	$222.80	$222.80	$222.80
Purchase #5	$39.62	10.739%	$43.8748	$43.87	$43.85	$43.90
Purchase #6	$103.71	5.499%	$109.413	$109.41	$109.40	$109.40
Purchase #7	$206.57	3.608%	$214.023	$214.02	$214.00	$214.00
7 purchase totals =	$953.43		$1,027.5526	$1,027.54	$1,027.55	$1,027.50