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	$91.93	10.547%	$101.6259	$101.63	$101.65	$101.60
Purchase #2	$214.79	4.102%	$223.6007	$223.60	$223.60	$223.60
Purchase #3	$73.50	12.414%	$82.6243	$82.62	$82.60	$82.60
Purchase #4	$33.57	10.537%	$37.1073	$37.11	$37.10	$37.10
Purchase #5	$184.44	8.581%	$200.2668	$200.27	$200.25	$200.30
Purchase #6	$87.47	4.680%	$91.5636	$91.56	$91.55	$91.60
Purchase #7	$147.67	6.806%	$157.7204	$157.72	$157.70	$157.70
7 purchase totals =	$833.37		$894.5090	$894.51	$894.45	$894.50