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	$177.87	10.248%	$196.0981	$196.10	$196.10	$196.10
Purchase #2	$86.85	12.231%	$97.4726	$97.47	$97.45	$97.50
Purchase #3	$144.26	3.555%	$149.3884	$149.39	$149.40	$149.40
Purchase #4	$163.43	7.308%	$175.3735	$175.37	$175.35	$175.40
Purchase #5	$213.98	10.435%	$236.3088	$236.31	$236.30	$236.30
Purchase #6	$175.40	9.211%	$191.5561	$191.56	$191.55	$191.60
Purchase #7	$14.51	6.732%	$15.4868	$15.49	$15.50	$15.50
7 purchase totals =	$976.30		$1,061.6843	$1,061.69	$1,061.65	$1,061.80