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	$244.35	7.125%	$261.7599	$261.76	$261.75	$261.80
Purchase #2	$67.54	5.651%	$71.3567	$71.36	$71.35	$71.40
Purchase #3	$95.57	9.693%	$104.8336	$104.83	$104.85	$104.80
Purchase #4	$97.79	13.604%	$111.0934	$111.09	$111.10	$111.10
Purchase #5	$240.71	12.130%	$269.9081	$269.91	$269.90	$269.90
Purchase #6	$94.34	4.749%	$98.8202	$98.82	$98.80	$98.80
Purchase #7	$186.65	5.402%	$196.7328	$196.73	$196.75	$196.70
7 purchase totals =	$1,026.95		$1,114.5047	$1,114.50	$1,114.50	$1,114.50