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	$196.56	11.848%	$219.8484	$219.85	$219.85	$219.80
Purchase #2	$56.29	13.658%	$63.9781	$63.98	$64.00	$64.00
Purchase #3	$96.71	9.141%	$105.5503	$105.55	$105.55	$105.60
Purchase #4	$169.47	7.108%	$181.5159	$181.52	$181.50	$181.50
Purchase #5	$121.33	13.721%	$137.9777	$137.98	$138.00	$138.00
Purchase #6	$216.81	3.284%	$223.93	$223.93	$223.95	$223.90
Purchase #7	$229.28	3.814%	$238.0247	$238.02	$238.00	$238.00
7 purchase totals =	$1,086.45		$1,170.8251	$1,170.83	$1,170.85	$1,170.80