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	$145.92	4.826%	$152.9621	$152.96	$152.95	$153.00
Purchase #2	$43.74	10.259%	$48.2273	$48.23	$48.25	$48.20
Purchase #3	$161.69	11.807%	$180.7807	$180.78	$180.80	$180.80
Purchase #4	$230.60	5.859%	$244.1109	$244.11	$244.10	$244.10
Purchase #5	$142.25	7.193%	$152.482	$152.48	$152.50	$152.50
Purchase #6	$54.47	9.161%	$59.46	$59.46	$59.45	$59.50
Purchase #7	$102.38	12.814%	$115.499	$115.50	$115.50	$115.50
7 purchase totals =	$881.05		$953.5220	$953.52	$953.55	$953.60