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	$188.68	13.516%	$214.182	$214.18	$214.20	$214.20
Purchase #2	$33.64	6.443%	$35.8074	$35.81	$35.80	$35.80
Purchase #3	$164.29	13.733%	$186.8519	$186.85	$186.85	$186.90
Purchase #4	$205.76	9.630%	$225.5747	$225.57	$225.55	$225.60
Purchase #5	$212.99	4.848%	$223.3158	$223.32	$223.30	$223.30
Purchase #6	$216.61	3.234%	$223.6152	$223.62	$223.60	$223.60
Purchase #7	$39.27	5.266%	$41.338	$41.34	$41.35	$41.30
7 purchase totals =	$1,061.24		$1,150.6850	$1,150.69	$1,150.65	$1,150.70