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	$215.66	12.435%	$242.4773	$242.48	$242.50	$242.50
Purchase #2	$73.85	8.647%	$80.2358	$80.24	$80.25	$80.20
Purchase #3	$92.35	4.536%	$96.539	$96.54	$96.55	$96.50
Purchase #4	$71.51	9.804%	$78.5208	$78.52	$78.50	$78.50
Purchase #5	$156.51	4.114%	$162.9488	$162.95	$162.95	$162.90
Purchase #6	$236.85	7.274%	$254.0785	$254.08	$254.10	$254.10
Purchase #7	$220.92	3.790%	$229.2929	$229.29	$229.30	$229.30
7 purchase totals =	$1,067.65		$1,144.0931	$1,144.10	$1,144.15	$1,144.00