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	$198.48	4.804%	$208.015	$208.02	$208.00	$208.00
Purchase #2	$90.25	9.384%	$98.7191	$98.72	$98.70	$98.70
Purchase #3	$173.93	8.825%	$189.2793	$189.28	$189.30	$189.30
Purchase #4	$139.33	6.845%	$148.8671	$148.87	$148.85	$148.90
Purchase #5	$193.30	10.612%	$213.813	$213.81	$213.80	$213.80
Purchase #6	$243.27	3.143%	$250.916	$250.92	$250.90	$250.90
Purchase #7	$233.60	9.724%	$256.3153	$256.32	$256.30	$256.30
7 purchase totals =	$1,272.16		$1,365.9248	$1,365.94	$1,365.85	$1,365.90