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	$213.34	7.665%	$229.6925	$229.69	$229.70	$229.70
Purchase #2	$67.81	7.262%	$72.7344	$72.73	$72.75	$72.70
Purchase #3	$130.69	11.337%	$145.5063	$145.51	$145.50	$145.50
Purchase #4	$152.29	12.323%	$171.0567	$171.06	$171.05	$171.10
Purchase #5	$10.44	4.231%	$10.8817	$10.88	$10.90	$10.90
Purchase #6	$192.87	12.269%	$216.5332	$216.53	$216.55	$216.50
Purchase #7	$146.88	4.183%	$153.024	$153.02	$153.00	$153.00
7 purchase totals =	$914.32		$999.4288	$999.42	$999.45	$999.40