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	$53.67	10.585%	$59.351	$59.35	$59.35	$59.40
Purchase #2	$46.39	3.823%	$48.1635	$48.16	$48.15	$48.20
Purchase #3	$135.65	6.867%	$144.9651	$144.97	$144.95	$145.00
Purchase #4	$134.52	8.357%	$145.7618	$145.76	$145.75	$145.80
Purchase #5	$180.98	8.610%	$196.5624	$196.56	$196.55	$196.60
Purchase #6	$213.37	8.418%	$231.3315	$231.33	$231.35	$231.30
Purchase #7	$227.93	4.516%	$238.2233	$238.22	$238.20	$238.20
7 purchase totals =	$992.51		$1,064.3586	$1,064.35	$1,064.30	$1,064.50