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	$250.98	4.602%	$262.5301	$262.53	$262.55	$262.50
Purchase #2	$74.34	5.354%	$78.3202	$78.32	$78.30	$78.30
Purchase #3	$111.69	12.354%	$125.4882	$125.49	$125.50	$125.50
Purchase #4	$49.93	6.599%	$53.2249	$53.22	$53.20	$53.20
Purchase #5	$171.69	7.835%	$185.1419	$185.14	$185.15	$185.10
Purchase #6	$67.36	9.573%	$73.8084	$73.81	$73.80	$73.80
Purchase #7	$177.56	5.839%	$187.9277	$187.93	$187.95	$187.90
7 purchase totals =	$903.55		$966.4414	$966.44	$966.45	$966.30