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	$59.71	4.741%	$62.5409	$62.54	$62.55	$62.50
Purchase #2	$29.59	8.342%	$32.0584	$32.06	$32.05	$32.10
Purchase #3	$224.76	8.343%	$243.5117	$243.51	$243.50	$243.50
Purchase #4	$144.70	11.651%	$161.559	$161.56	$161.55	$161.60
Purchase #5	$191.89	3.147%	$197.9288	$197.93	$197.95	$197.90
Purchase #6	$126.33	13.742%	$143.6903	$143.69	$143.70	$143.70
Purchase #7	$237.88	9.152%	$259.6508	$259.65	$259.65	$259.70
7 purchase totals =	$1,014.86		$1,100.9399	$1,100.94	$1,100.95	$1,101.00