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	$152.42	11.291%	$169.6297	$169.63	$169.65	$169.60
Purchase #2	$94.56	5.152%	$99.4317	$99.43	$99.45	$99.40
Purchase #3	$79.56	8.657%	$86.4475	$86.45	$86.45	$86.40
Purchase #4	$176.74	4.644%	$184.9478	$184.95	$184.95	$184.90
Purchase #5	$32.75	8.802%	$35.6327	$35.63	$35.65	$35.60
Purchase #6	$183.88	3.199%	$189.7623	$189.76	$189.75	$189.80
Purchase #7	$242.78	4.634%	$254.0304	$254.03	$254.05	$254.00
7 purchase totals =	$962.69		$1,019.8821	$1,019.88	$1,019.95	$1,019.70