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	$66.89	8.650%	$72.676	$72.68	$72.70	$72.70
Purchase #2	$68.95	4.210%	$71.8528	$71.85	$71.85	$71.90
Purchase #3	$142.64	6.803%	$152.3438	$152.34	$152.35	$152.30
Purchase #4	$212.74	3.546%	$220.2838	$220.28	$220.30	$220.30
Purchase #5	$127.63	5.200%	$134.2668	$134.27	$134.25	$134.30
Purchase #6	$159.93	9.316%	$174.8291	$174.83	$174.85	$174.80
Purchase #7	$198.83	11.353%	$221.4032	$221.40	$221.40	$221.40
7 purchase totals =	$977.61		$1,047.6555	$1,047.65	$1,047.70	$1,047.70