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	$180.54	7.444%	$193.9794	$193.98	$194.00	$194.00
Purchase #2	$96.64	4.663%	$101.1463	$101.15	$101.15	$101.10
Purchase #3	$183.31	7.374%	$196.8273	$196.83	$196.85	$196.80
Purchase #4	$243.53	4.416%	$254.2843	$254.28	$254.30	$254.30
Purchase #5	$62.44	13.501%	$70.87	$70.87	$70.85	$70.90
Purchase #6	$138.75	12.760%	$156.4545	$156.45	$156.45	$156.50
Purchase #7	$29.57	4.622%	$30.9367	$30.94	$30.95	$30.90
7 purchase totals =	$934.78		$1,004.4985	$1,004.50	$1,004.55	$1,004.50