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	$111.98	13.489%	$127.085	$127.09	$127.10	$127.10
Purchase #2	$145.41	4.734%	$152.2937	$152.29	$152.30	$152.30
Purchase #3	$98.79	4.564%	$103.2988	$103.30	$103.30	$103.30
Purchase #4	$242.55	3.519%	$251.0853	$251.09	$251.10	$251.10
Purchase #5	$207.53	4.857%	$217.6097	$217.61	$217.60	$217.60
Purchase #6	$214.27	11.519%	$238.9518	$238.95	$238.95	$239.00
Purchase #7	$196.49	3.592%	$203.5479	$203.55	$203.55	$203.50
7 purchase totals =	$1,217.02		$1,293.8722	$1,293.88	$1,293.90	$1,293.90