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	$9.63	11.608%	$10.7479	$10.75	$10.75	$10.70
Purchase #2	$85.72	6.454%	$91.2524	$91.25	$91.25	$91.30
Purchase #3	$209.95	8.349%	$227.4787	$227.48	$227.50	$227.50
Purchase #4	$210.61	6.235%	$223.7415	$223.74	$223.75	$223.70
Purchase #5	$18.41	6.531%	$19.6124	$19.61	$19.60	$19.60
Purchase #6	$71.54	10.130%	$78.787	$78.79	$78.80	$78.80
Purchase #7	$99.33	13.729%	$112.967	$112.97	$112.95	$113.00
7 purchase totals =	$705.19		$764.5869	$764.59	$764.60	$764.60