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	$182.61	4.803%	$191.3808	$191.38	$191.40	$191.40
Purchase #2	$154.80	12.386%	$173.9735	$173.97	$173.95	$174.00
Purchase #3	$171.83	7.554%	$184.81	$184.81	$184.80	$184.80
Purchase #4	$68.61	8.593%	$74.5057	$74.51	$74.50	$74.50
Purchase #5	$210.28	9.207%	$229.6405	$229.64	$229.65	$229.60
Purchase #6	$78.40	9.391%	$85.7625	$85.76	$85.75	$85.80
Purchase #7	$100.43	5.142%	$105.5941	$105.59	$105.60	$105.60
7 purchase totals =	$966.96		$1,045.6671	$1,045.66	$1,045.65	$1,045.70