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	$224.49	13.275%	$254.291	$254.29	$254.30	$254.30
Purchase #2	$92.54	7.667%	$99.635	$99.64	$99.65	$99.60
Purchase #3	$161.49	4.605%	$168.9266	$168.93	$168.95	$168.90
Purchase #4	$27.68	13.336%	$31.3714	$31.37	$31.35	$31.40
Purchase #5	$54.97	12.548%	$61.8676	$61.87	$61.85	$61.90
Purchase #6	$235.33	12.444%	$264.6145	$264.61	$264.60	$264.60
Purchase #7	$186.26	3.646%	$193.051	$193.05	$193.05	$193.10
7 purchase totals =	$982.76		$1,073.7571	$1,073.76	$1,073.75	$1,073.80