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	$171.53	7.688%	$184.7172	$184.72	$184.70	$184.70
Purchase #2	$148.70	11.124%	$165.2414	$165.24	$165.25	$165.20
Purchase #3	$73.38	13.205%	$83.0698	$83.07	$83.05	$83.10
Purchase #4	$143.26	3.168%	$147.7985	$147.80	$147.80	$147.80
Purchase #5	$160.95	3.797%	$167.0613	$167.06	$167.05	$167.10
Purchase #6	$168.81	12.828%	$190.4649	$190.46	$190.45	$190.50
Purchase #7	$94.85	4.478%	$99.0974	$99.10	$99.10	$99.10
7 purchase totals =	$961.48		$1,037.4505	$1,037.45	$1,037.40	$1,037.50