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	$188.29	4.346%	$196.4731	$196.47	$196.45	$196.50
Purchase #2	$109.62	8.525%	$118.9651	$118.97	$118.95	$119.00
Purchase #3	$210.67	6.253%	$223.8432	$223.84	$223.85	$223.80
Purchase #4	$166.67	11.251%	$185.422	$185.42	$185.40	$185.40
Purchase #5	$30.95	8.802%	$33.6742	$33.67	$33.65	$33.70
Purchase #6	$142.39	8.387%	$154.3322	$154.33	$154.35	$154.30
Purchase #7	$184.88	7.272%	$198.3245	$198.32	$198.30	$198.30
7 purchase totals =	$1,033.47		$1,111.0343	$1,111.02	$1,110.95	$1,111.00