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	$190.30	3.422%	$196.8121	$196.81	$196.80	$196.80
Purchase #2	$164.59	12.751%	$185.5769	$185.58	$185.60	$185.60
Purchase #3	$149.57	4.734%	$156.6506	$156.65	$156.65	$156.70
Purchase #4	$227.49	10.112%	$250.4938	$250.49	$250.50	$250.50
Purchase #5	$211.44	12.587%	$238.054	$238.05	$238.05	$238.10
Purchase #6	$115.57	10.416%	$127.6078	$127.61	$127.60	$127.60
Purchase #7	$94.73	13.729%	$107.7355	$107.74	$107.75	$107.70
7 purchase totals =	$1,153.69		$1,262.9307	$1,262.93	$1,262.95	$1,263.00