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	$63.93	13.631%	$72.6443	$72.64	$72.65	$72.60
Purchase #2	$152.98	12.114%	$171.512	$171.51	$171.50	$171.50
Purchase #3	$206.72	5.791%	$218.6912	$218.69	$218.70	$218.70
Purchase #4	$39.55	11.231%	$43.9919	$43.99	$44.00	$44.00
Purchase #5	$250.65	7.608%	$269.7195	$269.72	$269.70	$269.70
Purchase #6	$99.33	12.126%	$111.3748	$111.37	$111.35	$111.40
Purchase #7	$131.79	12.127%	$147.7722	$147.77	$147.75	$147.80
7 purchase totals =	$944.95		$1,035.7059	$1,035.69	$1,035.65	$1,035.70