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	$162.39	7.379%	$174.3728	$174.37	$174.35	$174.40
Purchase #2	$223.28	11.125%	$248.1199	$248.12	$248.10	$248.10
Purchase #3	$248.32	13.804%	$282.5981	$282.60	$282.60	$282.60
Purchase #4	$66.60	10.620%	$73.6729	$73.67	$73.65	$73.70
Purchase #5	$198.51	11.400%	$221.1401	$221.14	$221.15	$221.10
Purchase #6	$178.97	9.770%	$196.4554	$196.46	$196.45	$196.50
Purchase #7	$130.76	10.788%	$144.8664	$144.87	$144.85	$144.90
7 purchase totals =	$1,208.83		$1,341.2256	$1,341.23	$1,341.15	$1,341.30