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	$191.57	3.485%	$198.2462	$198.25	$198.25	$198.20
Purchase #2	$88.81	9.112%	$96.9024	$96.90	$96.90	$96.90
Purchase #3	$12.41	10.305%	$13.6889	$13.69	$13.70	$13.70
Purchase #4	$154.82	10.771%	$171.4957	$171.50	$171.50	$171.50
Purchase #5	$102.50	9.175%	$111.9044	$111.90	$111.90	$111.90
Purchase #6	$240.88	4.547%	$251.8328	$251.83	$251.85	$251.80
Purchase #7	$198.45	4.135%	$206.6559	$206.66	$206.65	$206.70
7 purchase totals =	$989.44		$1,050.7263	$1,050.73	$1,050.75	$1,050.70