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	$186.38	5.670%	$196.9477	$196.95	$196.95	$196.90
Purchase #2	$167.67	13.332%	$190.0238	$190.02	$190.00	$190.00
Purchase #3	$41.61	6.148%	$44.1682	$44.17	$44.15	$44.20
Purchase #4	$184.30	3.753%	$191.2168	$191.22	$191.20	$191.20
Purchase #5	$142.67	6.450%	$151.8722	$151.87	$151.85	$151.90
Purchase #6	$64.54	9.301%	$70.5429	$70.54	$70.55	$70.50
Purchase #7	$208.40	11.123%	$231.5803	$231.58	$231.60	$231.60
7 purchase totals =	$995.57		$1,076.3519	$1,076.35	$1,076.30	$1,076.30