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	$246.58	11.430%	$274.7641	$274.76	$274.75	$274.80
Purchase #2	$12.45	10.493%	$13.7564	$13.76	$13.75	$13.80
Purchase #3	$113.74	12.454%	$127.9052	$127.91	$127.90	$127.90
Purchase #4	$185.83	3.126%	$191.639	$191.64	$191.65	$191.60
Purchase #5	$224.82	3.677%	$233.0866	$233.09	$233.10	$233.10
Purchase #6	$67.90	11.164%	$75.4804	$75.48	$75.50	$75.50
Purchase #7	$97.44	8.209%	$105.4388	$105.44	$105.45	$105.40
7 purchase totals =	$948.76		$1,022.0705	$1,022.08	$1,022.10	$1,022.10