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	$59.78	3.712%	$61.999	$62.00	$62.00	$62.00
Purchase #2	$152.53	13.453%	$173.0499	$173.05	$173.05	$173.00
Purchase #3	$244.82	11.822%	$273.7626	$273.76	$273.75	$273.80
Purchase #4	$75.63	7.709%	$81.4603	$81.46	$81.45	$81.50
Purchase #5	$156.65	7.591%	$168.5413	$168.54	$168.55	$168.50
Purchase #6	$197.99	10.428%	$218.6364	$218.64	$218.65	$218.60
Purchase #7	$152.61	8.187%	$165.1042	$165.10	$165.10	$165.10
7 purchase totals =	$1,040.01		$1,142.5537	$1,142.55	$1,142.55	$1,142.50