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	$171.56	4.813%	$179.8172	$179.82	$179.80	$179.80
Purchase #2	$68.50	6.382%	$72.8717	$72.87	$72.85	$72.90
Purchase #3	$185.75	5.627%	$196.2022	$196.20	$196.20	$196.20
Purchase #4	$203.31	12.667%	$229.0633	$229.06	$229.05	$229.10
Purchase #5	$176.65	13.285%	$200.118	$200.12	$200.10	$200.10
Purchase #6	$88.25	11.668%	$98.547	$98.55	$98.55	$98.50
Purchase #7	$184.68	6.511%	$196.7045	$196.70	$196.70	$196.70
7 purchase totals =	$1,078.70		$1,173.3239	$1,173.32	$1,173.25	$1,173.30