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	$212.68	3.180%	$219.4432	$219.44	$219.45	$219.40
Purchase #2	$133.57	3.246%	$137.9057	$137.91	$137.90	$137.90
Purchase #3	$91.93	8.642%	$99.8746	$99.87	$99.85	$99.90
Purchase #4	$142.84	5.325%	$150.4462	$150.45	$150.45	$150.40
Purchase #5	$133.78	4.296%	$139.5272	$139.53	$139.55	$139.50
Purchase #6	$114.79	11.258%	$127.7131	$127.71	$127.70	$127.70
Purchase #7	$190.73	4.627%	$199.5551	$199.56	$199.55	$199.60
7 purchase totals =	$1,020.32		$1,074.4651	$1,074.47	$1,074.45	$1,074.40