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	$151.29	7.687%	$162.9197	$162.92	$162.90	$162.90
Purchase #2	$114.28	7.676%	$123.0521	$123.05	$123.05	$123.10
Purchase #3	$75.69	9.406%	$82.8094	$82.81	$82.80	$82.80
Purchase #4	$143.42	5.516%	$151.331	$151.33	$151.35	$151.30
Purchase #5	$118.62	10.427%	$130.9885	$130.99	$131.00	$131.00
Purchase #6	$234.26	9.161%	$255.7206	$255.72	$255.70	$255.70
Purchase #7	$180.56	11.680%	$201.6494	$201.65	$201.65	$201.60
7 purchase totals =	$1,018.12		$1,108.4707	$1,108.47	$1,108.45	$1,108.40