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	$56.81	10.627%	$62.8472	$62.85	$62.85	$62.80
Purchase #2	$56.76	7.253%	$60.8768	$60.88	$60.90	$60.90
Purchase #3	$207.45	10.587%	$229.4127	$229.41	$229.40	$229.40
Purchase #4	$118.96	12.658%	$134.018	$134.02	$134.00	$134.00
Purchase #5	$105.89	3.204%	$109.2827	$109.28	$109.30	$109.30
Purchase #6	$209.77	5.706%	$221.7395	$221.74	$221.75	$221.70
Purchase #7	$176.82	7.839%	$190.6809	$190.68	$190.70	$190.70
7 purchase totals =	$932.46		$1,008.8578	$1,008.86	$1,008.90	$1,008.80