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	$97.59	6.593%	$104.0241	$104.02	$104.00	$104.00
Purchase #2	$184.61	6.563%	$196.726	$196.73	$196.75	$196.70
Purchase #3	$25.25	13.677%	$28.7034	$28.70	$28.70	$28.70
Purchase #4	$55.98	4.480%	$58.4879	$58.49	$58.50	$58.50
Purchase #5	$128.40	4.253%	$133.8609	$133.86	$133.85	$133.90
Purchase #6	$59.44	13.819%	$67.654	$67.65	$67.65	$67.70
Purchase #7	$215.46	8.418%	$233.5974	$233.60	$233.60	$233.60
7 purchase totals =	$766.73		$823.0537	$823.05	$823.05	$823.10