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	$162.54	12.117%	$182.235	$182.24	$182.25	$182.20
Purchase #2	$143.48	11.549%	$160.0505	$160.05	$160.05	$160.10
Purchase #3	$89.29	7.175%	$95.6966	$95.70	$95.70	$95.70
Purchase #4	$156.69	9.436%	$171.4753	$171.48	$171.50	$171.50
Purchase #5	$147.85	13.834%	$168.3036	$168.30	$168.30	$168.30
Purchase #6	$142.79	10.356%	$157.5773	$157.58	$157.60	$157.60
Purchase #7	$103.53	10.167%	$114.0559	$114.06	$114.05	$114.10
7 purchase totals =	$946.17		$1,049.3942	$1,049.41	$1,049.45	$1,049.50