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	$58.55	5.761%	$61.9231	$61.92	$61.90	$61.90
Purchase #2	$172.58	4.337%	$180.0648	$180.06	$180.05	$180.10
Purchase #3	$242.55	3.830%	$251.8397	$251.84	$251.85	$251.80
Purchase #4	$176.56	10.409%	$194.9381	$194.94	$194.95	$194.90
Purchase #5	$165.85	5.218%	$174.5041	$174.50	$174.50	$174.50
Purchase #6	$99.77	3.352%	$103.1143	$103.11	$103.10	$103.10
Purchase #7	$88.76	7.592%	$95.4987	$95.50	$95.50	$95.50
7 purchase totals =	$1,004.62		$1,061.8828	$1,061.87	$1,061.85	$1,061.80