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	$223.77	8.805%	$243.4729	$243.47	$243.45	$243.50
Purchase #2	$173.63	8.563%	$188.4979	$188.50	$188.50	$188.50
Purchase #3	$126.77	13.427%	$143.7914	$143.79	$143.80	$143.80
Purchase #4	$69.54	4.163%	$72.435	$72.44	$72.45	$72.40
Purchase #5	$229.79	13.814%	$261.5332	$261.53	$261.55	$261.50
Purchase #6	$55.55	5.364%	$58.5297	$58.53	$58.55	$58.50
Purchase #7	$195.95	8.330%	$212.2726	$212.27	$212.25	$212.30
7 purchase totals =	$1,075.00		$1,180.5327	$1,180.53	$1,180.55	$1,180.50