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	$211.58	6.699%	$225.7537	$225.75	$225.75	$225.80
Purchase #2	$215.51	3.344%	$222.7167	$222.72	$222.70	$222.70
Purchase #3	$176.58	5.490%	$186.2742	$186.27	$186.25	$186.30
Purchase #4	$55.41	13.507%	$62.8942	$62.89	$62.90	$62.90
Purchase #5	$153.30	12.131%	$171.8968	$171.90	$171.90	$171.90
Purchase #6	$98.50	7.716%	$106.1003	$106.10	$106.10	$106.10
Purchase #7	$141.94	7.545%	$152.6494	$152.65	$152.65	$152.60
7 purchase totals =	$1,052.82		$1,128.2853	$1,128.28	$1,128.25	$1,128.30