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	$213.61	11.269%	$237.6817	$237.68	$237.70	$237.70
Purchase #2	$176.33	11.423%	$196.4722	$196.47	$196.45	$196.50
Purchase #3	$128.54	12.159%	$144.1692	$144.17	$144.15	$144.20
Purchase #4	$105.35	12.304%	$118.3123	$118.31	$118.30	$118.30
Purchase #5	$9.93	9.603%	$10.8836	$10.88	$10.90	$10.90
Purchase #6	$231.81	7.315%	$248.7669	$248.77	$248.75	$248.80
Purchase #7	$130.62	9.281%	$142.7428	$142.74	$142.75	$142.70
7 purchase totals =	$996.19		$1,099.0287	$1,099.02	$1,099.00	$1,099.10