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	$32.35	10.844%	$35.858	$35.86	$35.85	$35.90
Purchase #2	$6.46	9.793%	$7.0926	$7.09	$7.10	$7.10
Purchase #3	$189.25	7.436%	$203.3226	$203.32	$203.30	$203.30
Purchase #4	$89.32	11.292%	$99.406	$99.41	$99.40	$99.40
Purchase #5	$214.54	9.288%	$234.4665	$234.47	$234.45	$234.50
Purchase #6	$175.43	11.144%	$194.9799	$194.98	$195.00	$195.00
Purchase #7	$62.38	11.147%	$69.3335	$69.33	$69.35	$69.30
7 purchase totals =	$769.73		$844.4591	$844.46	$844.45	$844.50