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	$175.86	3.353%	$181.7566	$181.76	$181.75	$181.80
Purchase #2	$32.75	3.273%	$33.8219	$33.82	$33.80	$33.80
Purchase #3	$85.44	12.667%	$96.2627	$96.26	$96.25	$96.30
Purchase #4	$195.47	11.178%	$217.3196	$217.32	$217.30	$217.30
Purchase #5	$160.94	3.679%	$166.861	$166.86	$166.85	$166.90
Purchase #6	$223.56	8.829%	$243.2981	$243.30	$243.30	$243.30
Purchase #7	$111.28	6.505%	$118.5188	$118.52	$118.50	$118.50
7 purchase totals =	$985.30		$1,057.8387	$1,057.84	$1,057.75	$1,057.90