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	$95.96	10.424%	$105.9629	$105.96	$105.95	$106.00
Purchase #2	$38.39	4.667%	$40.1817	$40.18	$40.20	$40.20
Purchase #3	$231.72	4.375%	$241.8578	$241.86	$241.85	$241.90
Purchase #4	$72.48	7.846%	$78.1668	$78.17	$78.15	$78.20
Purchase #5	$64.57	11.850%	$72.2215	$72.22	$72.20	$72.20
Purchase #6	$223.35	11.121%	$248.1888	$248.19	$248.20	$248.20
Purchase #7	$243.27	6.753%	$259.698	$259.70	$259.70	$259.70
7 purchase totals =	$969.74		$1,046.2775	$1,046.28	$1,046.25	$1,046.40