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	$130.69	10.234%	$144.0648	$144.06	$144.05	$144.10
Purchase #2	$14.36	3.744%	$14.8976	$14.90	$14.90	$14.90
Purchase #3	$8.61	3.471%	$8.9089	$8.91	$8.90	$8.90
Purchase #4	$144.56	3.807%	$150.0634	$150.06	$150.05	$150.10
Purchase #5	$151.90	11.607%	$169.531	$169.53	$169.55	$169.50
Purchase #6	$102.68	11.471%	$114.4584	$114.46	$114.45	$114.50
Purchase #7	$183.64	9.165%	$200.4706	$200.47	$200.45	$200.50
7 purchase totals =	$736.44		$802.3947	$802.39	$802.35	$802.50