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	$233.59	3.359%	$241.4363	$241.44	$241.45	$241.40
Purchase #2	$164.50	6.148%	$174.6135	$174.61	$174.60	$174.60
Purchase #3	$183.33	11.128%	$203.731	$203.73	$203.75	$203.70
Purchase #4	$105.66	5.280%	$111.2388	$111.24	$111.25	$111.20
Purchase #5	$88.59	8.737%	$96.3301	$96.33	$96.35	$96.30
Purchase #6	$38.64	6.739%	$41.2439	$41.24	$41.25	$41.20
Purchase #7	$228.44	6.801%	$243.9762	$243.98	$244.00	$244.00
7 purchase totals =	$1,042.75		$1,112.5698	$1,112.57	$1,112.65	$1,112.40