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	$52.25	10.543%	$57.7587	$57.76	$57.75	$57.80
Purchase #2	$9.53	10.547%	$10.5351	$10.54	$10.55	$10.50
Purchase #3	$30.55	7.127%	$32.7273	$32.73	$32.75	$32.70
Purchase #4	$177.49	10.750%	$196.5702	$196.57	$196.55	$196.60
Purchase #5	$228.61	6.710%	$243.9497	$243.95	$243.95	$243.90
Purchase #6	$70.41	11.660%	$78.6198	$78.62	$78.60	$78.60
Purchase #7	$132.45	11.282%	$147.393	$147.39	$147.40	$147.40
7 purchase totals =	$701.29		$767.5538	$767.56	$767.55	$767.50