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	$147.42	13.429%	$167.217	$167.22	$167.20	$167.20
Purchase #2	$53.45	7.665%	$57.5469	$57.55	$57.55	$57.50
Purchase #3	$93.87	8.269%	$101.6321	$101.63	$101.65	$101.60
Purchase #4	$207.29	4.398%	$216.4066	$216.41	$216.40	$216.40
Purchase #5	$47.40	6.688%	$50.5701	$50.57	$50.55	$50.60
Purchase #6	$53.61	11.171%	$59.5988	$59.60	$59.60	$59.60
Purchase #7	$78.33	6.192%	$83.1802	$83.18	$83.20	$83.20
7 purchase totals =	$681.37		$736.1517	$736.16	$736.15	$736.10