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	$60.94	5.568%	$64.3331	$64.33	$64.35	$64.30
Purchase #2	$48.62	10.214%	$53.586	$53.59	$53.60	$53.60
Purchase #3	$124.72	4.602%	$130.4596	$130.46	$130.45	$130.50
Purchase #4	$179.66	3.170%	$185.3552	$185.36	$185.35	$185.40
Purchase #5	$241.54	13.384%	$273.8677	$273.87	$273.85	$273.90
Purchase #6	$222.32	3.412%	$229.9056	$229.91	$229.90	$229.90
Purchase #7	$89.48	5.461%	$94.3665	$94.37	$94.35	$94.40
7 purchase totals =	$967.28		$1,031.8737	$1,031.89	$1,031.85	$1,032.00