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	$176.25	11.374%	$196.2967	$196.30	$196.30	$196.30
Purchase #2	$249.80	5.811%	$264.3159	$264.32	$264.30	$264.30
Purchase #3	$238.40	4.289%	$248.625	$248.63	$248.65	$248.60
Purchase #4	$37.60	13.623%	$42.7222	$42.72	$42.70	$42.70
Purchase #5	$248.85	3.283%	$257.0197	$257.02	$257.00	$257.00
Purchase #6	$32.72	3.218%	$33.7729	$33.77	$33.75	$33.80
Purchase #7	$18.28	8.669%	$19.8647	$19.86	$19.85	$19.90
7 purchase totals =	$1,001.90		$1,062.6171	$1,062.62	$1,062.55	$1,062.60