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	$116.38	8.679%	$126.4806	$126.48	$126.50	$126.50
Purchase #2	$33.89	11.588%	$37.8172	$37.82	$37.80	$37.80
Purchase #3	$167.52	5.463%	$176.6716	$176.67	$176.65	$176.70
Purchase #4	$198.56	11.219%	$220.8364	$220.84	$220.85	$220.80
Purchase #5	$29.86	8.286%	$32.3342	$32.33	$32.35	$32.30
Purchase #6	$216.53	3.393%	$223.8769	$223.88	$223.90	$223.90
Purchase #7	$191.81	6.572%	$204.4158	$204.42	$204.40	$204.40
7 purchase totals =	$954.55		$1,022.4327	$1,022.44	$1,022.45	$1,022.40