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	$179.43	10.868%	$198.9305	$198.93	$198.95	$198.90
Purchase #2	$188.44	9.298%	$205.9612	$205.96	$205.95	$206.00
Purchase #3	$213.52	4.496%	$223.1199	$223.12	$223.10	$223.10
Purchase #4	$55.66	7.423%	$59.7916	$59.79	$59.80	$59.80
Purchase #5	$148.57	5.520%	$156.7711	$156.77	$156.75	$156.80
Purchase #6	$139.57	5.192%	$146.8165	$146.82	$146.80	$146.80
Purchase #7	$160.61	4.203%	$167.3604	$167.36	$167.35	$167.40
7 purchase totals =	$1,085.80		$1,158.7512	$1,158.75	$1,158.70	$1,158.80