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	$181.38	10.779%	$200.931	$200.93	$200.95	$200.90
Purchase #2	$204.90	5.730%	$216.6408	$216.64	$216.65	$216.60
Purchase #3	$59.51	13.686%	$67.6545	$67.65	$67.65	$67.70
Purchase #4	$144.59	7.456%	$155.3706	$155.37	$155.35	$155.40
Purchase #5	$220.76	3.461%	$228.4005	$228.40	$228.40	$228.40
Purchase #6	$226.39	7.778%	$243.9986	$244.00	$244.00	$244.00
Purchase #7	$48.77	13.106%	$55.1618	$55.16	$55.15	$55.20
7 purchase totals =	$1,086.30		$1,168.1578	$1,168.15	$1,168.15	$1,168.20