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	$103.39	8.285%	$111.9559	$111.96	$111.95	$112.00
Purchase #2	$224.89	13.130%	$254.4181	$254.42	$254.40	$254.40
Purchase #3	$90.81	9.309%	$99.2635	$99.26	$99.25	$99.30
Purchase #4	$180.98	8.396%	$196.1751	$196.18	$196.20	$196.20
Purchase #5	$104.66	6.121%	$111.0662	$111.07	$111.05	$111.10
Purchase #6	$127.42	3.319%	$131.6491	$131.65	$131.65	$131.60
Purchase #7	$129.60	8.214%	$140.2453	$140.25	$140.25	$140.20
7 purchase totals =	$961.75		$1,044.7732	$1,044.79	$1,044.75	$1,044.80