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	$133.81	13.581%	$151.9827	$151.98	$152.00	$152.00
Purchase #2	$14.25	11.439%	$15.8801	$15.88	$15.90	$15.90
Purchase #3	$247.33	10.635%	$273.6335	$273.63	$273.65	$273.60
Purchase #4	$51.96	3.680%	$53.8721	$53.87	$53.85	$53.90
Purchase #5	$78.78	4.678%	$82.4653	$82.47	$82.45	$82.50
Purchase #6	$105.29	3.753%	$109.2415	$109.24	$109.25	$109.20
Purchase #7	$176.37	10.234%	$194.4197	$194.42	$194.40	$194.40
7 purchase totals =	$807.79		$881.4949	$881.49	$881.50	$881.50