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	$69.44	4.652%	$72.6703	$72.67	$72.65	$72.70
Purchase #2	$183.42	3.188%	$189.2674	$189.27	$189.25	$189.30
Purchase #3	$13.44	7.520%	$14.4507	$14.45	$14.45	$14.50
Purchase #4	$152.57	7.667%	$164.2675	$164.27	$164.25	$164.30
Purchase #5	$203.65	12.321%	$228.7417	$228.74	$228.75	$228.70
Purchase #6	$90.74	5.489%	$95.7207	$95.72	$95.70	$95.70
Purchase #7	$112.32	13.458%	$127.436	$127.44	$127.45	$127.40
7 purchase totals =	$825.58		$892.5543	$892.56	$892.50	$892.60