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	$167.27	4.629%	$175.0129	$175.01	$175.00	$175.00
Purchase #2	$78.95	13.332%	$89.4756	$89.48	$89.50	$89.50
Purchase #3	$189.68	4.398%	$198.0221	$198.02	$198.00	$198.00
Purchase #4	$227.91	13.503%	$258.6847	$258.68	$258.70	$258.70
Purchase #5	$129.57	3.705%	$134.3706	$134.37	$134.35	$134.40
Purchase #6	$167.38	4.203%	$174.415	$174.42	$174.40	$174.40
Purchase #7	$108.31	7.483%	$116.4148	$116.41	$116.40	$116.40
7 purchase totals =	$1,069.07		$1,146.3957	$1,146.39	$1,146.35	$1,146.40