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	$219.54	7.480%	$235.9616	$235.96	$235.95	$236.00
Purchase #2	$165.58	6.118%	$175.7102	$175.71	$175.70	$175.70
Purchase #3	$38.35	11.477%	$42.7514	$42.75	$42.75	$42.80
Purchase #4	$173.76	12.828%	$196.0499	$196.05	$196.05	$196.00
Purchase #5	$37.96	6.356%	$40.3727	$40.37	$40.35	$40.40
Purchase #6	$231.27	4.488%	$241.6494	$241.65	$241.65	$241.60
Purchase #7	$210.28	4.670%	$220.1001	$220.10	$220.10	$220.10
7 purchase totals =	$1,076.74		$1,152.5953	$1,152.59	$1,152.55	$1,152.60