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	$175.35	11.785%	$196.015	$196.02	$196.00	$196.00
Purchase #2	$71.94	8.804%	$78.2736	$78.27	$78.25	$78.30
Purchase #3	$116.79	11.653%	$130.3995	$130.40	$130.40	$130.40
Purchase #4	$227.78	6.143%	$241.7725	$241.77	$241.75	$241.80
Purchase #5	$165.34	13.198%	$187.1616	$187.16	$187.15	$187.20
Purchase #6	$235.53	3.559%	$243.9125	$243.91	$243.90	$243.90
Purchase #7	$99.70	3.659%	$103.348	$103.35	$103.35	$103.30
7 purchase totals =	$1,092.43		$1,180.8827	$1,180.88	$1,180.80	$1,180.90