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	$148.70	3.443%	$153.8197	$153.82	$153.80	$153.80
Purchase #2	$235.75	4.240%	$245.7458	$245.75	$245.75	$245.70
Purchase #3	$18.94	12.418%	$21.292	$21.29	$21.30	$21.30
Purchase #4	$63.98	13.404%	$72.5559	$72.56	$72.55	$72.60
Purchase #5	$35.55	4.273%	$37.0691	$37.07	$37.05	$37.10
Purchase #6	$202.92	11.321%	$225.8926	$225.89	$225.90	$225.90
Purchase #7	$244.38	3.164%	$252.1122	$252.11	$252.10	$252.10
7 purchase totals =	$950.22		$1,008.4873	$1,008.49	$1,008.45	$1,008.50