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	$118.40	8.401%	$128.3468	$128.35	$128.35	$128.30
Purchase #2	$216.47	11.563%	$241.5004	$241.50	$241.50	$241.50
Purchase #3	$96.71	3.300%	$99.9014	$99.90	$99.90	$99.90
Purchase #4	$55.87	10.740%	$61.8704	$61.87	$61.85	$61.90
Purchase #5	$92.72	3.215%	$95.7009	$95.70	$95.70	$95.70
Purchase #6	$214.50	6.543%	$228.5347	$228.53	$228.55	$228.50
Purchase #7	$231.34	8.812%	$251.7257	$251.73	$251.75	$251.70
7 purchase totals =	$1,026.01		$1,107.5803	$1,107.58	$1,107.60	$1,107.50