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	$141.88	7.614%	$152.6827	$152.68	$152.70	$152.70
Purchase #2	$167.47	11.384%	$186.5348	$186.53	$186.55	$186.50
Purchase #3	$6.54	13.755%	$7.4396	$7.44	$7.45	$7.40
Purchase #4	$41.29	13.233%	$46.7539	$46.75	$46.75	$46.80
Purchase #5	$200.98	7.488%	$216.0294	$216.03	$216.05	$216.00
Purchase #6	$106.35	4.748%	$111.3995	$111.40	$111.40	$111.40
Purchase #7	$41.82	5.871%	$44.2753	$44.28	$44.30	$44.30
7 purchase totals =	$706.33		$765.1152	$765.11	$765.20	$765.10