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	$149.60	13.281%	$169.4684	$169.47	$169.45	$169.50
Purchase #2	$14.42	7.414%	$15.4891	$15.49	$15.50	$15.50
Purchase #3	$79.28	12.863%	$89.4778	$89.48	$89.50	$89.50
Purchase #4	$13.38	5.656%	$14.1368	$14.14	$14.15	$14.10
Purchase #5	$99.76	5.582%	$105.3286	$105.33	$105.35	$105.30
Purchase #6	$132.31	13.352%	$149.976	$149.98	$150.00	$150.00
Purchase #7	$166.38	12.701%	$187.5119	$187.51	$187.50	$187.50
7 purchase totals =	$655.13		$731.3886	$731.40	$731.45	$731.40